7.0% actually 3.69%?

zagfles

OceanSound said:

zagfles said:

OceanSound said:

zagfles said:

OceanSound said:

Albermarle said:

Basically if you have £3600 to save as a lump sum, you would be better just to put it a normal savings account for a one year fix. This FD account is more for people who are regular monthly savers.

Using the drip feed method where you deposit the £3600 in a current account like Kroo then drip feed the monthly payment of £300 in to First Direct Current Account then in to Regular Saver (RS) brings in a higher profit than saving it as a lump sum. 

I checked the moneyfacts website for the highest interest paying place for a 1 year Fixed deposit for £3600. It is Hampshire trust Bank paying 4.91%. So this would be ---> 3600 x 0.0491 = £176.76

However, if using the drip feed method. First Direct RS will pay £136.50 (source: https://www.firstdirect.com/savings-and-investments/savings/regular-saver-account/ ) notice though, if you scroll down the page under key product info it says:

• total deposit at the end of 12 months: £3,600....

• balance at the end of 12 months: £3,726.50

£3,726.50 - £3600  is £126.50. So there appears to be a discrepancy. 

Anyway if we use Kroo current account which pays 3.33%, then for the 12 months the interest works out to be  £58.29. I calculated this figure month by month. e.g. staring off with £3300 (because £300 of the £3600 will be paid in to FD to start with), then every month deducted £300 from the £3300 and worked out the interest every month for the 12 months then added the figures together. 

Now, we add £58.29 to £126.50 (interest from FD RS) and the combined total is £184.79 - which is more than the profit from the 1 year fixed rate. Note this is using the FD RS interest of £126.50 not £136.50. If we use the latter, the profit will be even more. 

BTW, I've a spreadsheet where I use this formula:

=SUM(12*E10)*C10/12*6.5

to calculate the interest from a regular saver. When I plug in the values. i.e. the interest divided by 100 (in this case 0.07) and the monthly deposit amount (in this case 300), it gives me a result of 136.50. 

As another check I then visit: https://www.moneysavingexpert.com/savings/regular-savings-calculator/

and plug in the values, and the result is £135. So, the £136.50 or £135 figure seems correct, not the £126.50. Probably a typo, and the 'balance at the end of 12 months: ' should state £3,736.50.

It'll vary a bit due to different month lengths, weekends etc. £136.50 assumes equal length months and payments going in one the same date every month.

It won't vary by exactly £10 due to different month lengths, weekends etc. 

Btw, I'm presuming you are referring to the discrepancy between £136.50 and £126.50, as your reply didn't say you are referring to the difference between FD RS website (including my spreadsheet formula) £136.50 and MSE website £135.00.

No probably less than £1 or so, just making the point the figure won't be exact.

Oh! I see. So, the FD website £10 discrepancy is a typo?

Probably, or maybe a worst case scenario, although £10 seems a bit high.

OceanSound

zagfles said:

OceanSound said:

zagfles said:

OceanSound said:

zagfles said:

OceanSound said:

Albermarle said:

Basically if you have £3600 to save as a lump sum, you would be better just to put it a normal savings account for a one year fix. This FD account is more for people who are regular monthly savers.

Using the drip feed method where you deposit the £3600 in a current account like Kroo then drip feed the monthly payment of £300 in to First Direct Current Account then in to Regular Saver (RS) brings in a higher profit than saving it as a lump sum. 

I checked the moneyfacts website for the highest interest paying place for a 1 year Fixed deposit for £3600. It is Hampshire trust Bank paying 4.91%. So this would be ---> 3600 x 0.0491 = £176.76

However, if using the drip feed method. First Direct RS will pay £136.50 (source: https://www.firstdirect.com/savings-and-investments/savings/regular-saver-account/ ) notice though, if you scroll down the page under key product info it says:

• total deposit at the end of 12 months: £3,600....

• balance at the end of 12 months: £3,726.50

£3,726.50 - £3600  is £126.50. So there appears to be a discrepancy. 

Anyway if we use Kroo current account which pays 3.33%, then for the 12 months the interest works out to be  £58.29. I calculated this figure month by month. e.g. staring off with £3300 (because £300 of the £3600 will be paid in to FD to start with), then every month deducted £300 from the £3300 and worked out the interest every month for the 12 months then added the figures together. 

Now, we add £58.29 to £126.50 (interest from FD RS) and the combined total is £184.79 - which is more than the profit from the 1 year fixed rate. Note this is using the FD RS interest of £126.50 not £136.50. If we use the latter, the profit will be even more. 

BTW, I've a spreadsheet where I use this formula:

=SUM(12*E10)*C10/12*6.5

to calculate the interest from a regular saver. When I plug in the values. i.e. the interest divided by 100 (in this case 0.07) and the monthly deposit amount (in this case 300), it gives me a result of 136.50. 

As another check I then visit: https://www.moneysavingexpert.com/savings/regular-savings-calculator/

and plug in the values, and the result is £135. So, the £136.50 or £135 figure seems correct, not the £126.50. Probably a typo, and the 'balance at the end of 12 months: ' should state £3,736.50.

It'll vary a bit due to different month lengths, weekends etc. £136.50 assumes equal length months and payments going in one the same date every month.

It won't vary by exactly £10 due to different month lengths, weekends etc. 

Btw, I'm presuming you are referring to the discrepancy between £136.50 and £126.50, as your reply didn't say you are referring to the difference between FD RS website (including my spreadsheet formula) £136.50 and MSE website £135.00.

No probably less than £1 or so, just making the point the figure won't be exact.

Oh! I see. So, the FD website £10 discrepancy is a typo?

Probably, or maybe a worst case scenario, although £10 seems a bit high.

Really? Several bank holidays. E.g. due to coronation and ...<scratching my head now>

Edit: worse case scenario has magically or by coincidence come up with a £10 difference?

On that webpage it tells us the assumptions. If FD used different assumptions to work out a 'worse case' scenario, FD would need to make us aware!

AmityNeon

zagfles said:

AmityNeon said:

zagfles said:

AmityNeon said:

zagfles said:

AmityNeon said:

zagfles said:

AmityNeon said:

zagfles said:

There are other examples. Eg

x^2 = y^2.

So logically, x = y, right? Same operation both sides?

No, because the concept of a double negative is still logical. If I owe three people a negative debt of £3 each, it equally means three people each owe me £3. I can go up uphill forwards, or turn my body around and walk backwards (whilst still moving uphill).

That's certainly logical. But I was talking about the general "logical" principle of applying the same operation to both sides of the equation.

What about it? You must apply the same operation to both sides of an equation; that has no relation to forcing logic to somehow deduce that x = y.

OK, using your logic, work out the amount of energy your solar panels would generate on a sunny day. I guarantee you won't be able to do it without using calculus. If you can work out how to use calculus from first principles without being taught it or looking it up, I'll be mighty impressed!

I'm not sure what point you think I made for you to steer this conversation towards calculating the amount of energy solar panels can generate on a sunny day, or how that is relevant to applying the same operations to both sides of an equation to maintain logical consistency.

You seem to be under the impression I believe logic renders maths useless, or something. Logic is simply the basis of maths; you cannot study maths successfully without being a logical and critical thinker. You also don't need to like or study maths to use basic arithmetic and logic to understand personal finance at the consumer level.

Yes you do. That's the point. I've given enough examples where you really do need to have done some study of maths or at least have been taught or looked up mathematical techniques. Unless you really are Einstein and can work all these things out from first principles. How much energy your solar panels generate is a personal finance issue. To work it out, you need calculus. It's an extreme example, but other stuff like drawdown etc does need mathematical techniques which can be taught or looked up. There's no point reinventing the wheel.

I only have a GCSE in maths, which the vast majority of adults also have (or equivalent), and I managed to derive the Regular Saver formula for myself. I just remembered the basic arithmetic and algebra I was taught in school decades ago; I didn't look anything else up, and there was no calculator either. I am no Einstein or child prodigy, or even academically gifted. My career does not involve a related discipline. What I did have, was the attitude that I could probably do it.

Well, exactly! You didn't use "innate logic", you remembered techniques you were taught. That was my point.

I did A-level maths, and I could do more advanced stuff like work out the energy solar panels generate in a day using calculus, because I was taught it, not through "innate logic".

I was never taught how to derive a generic formula to calculate whether it would be beneficial to close and renew a Regular Saver at a higher rate of interest. I applied my knowledge of basic arithmetic and algebra taught in compulsory education to logically deduce a formula specific to a particular use case in the context of Regular Savers. I'm just average. There are young child prodigies who write formulas in the sand on the beach whilst their siblings build sandcastles.

Maths is a formal system based on axioms and rules of inference. It's through logic that I know that the derived formula is correct, unlike for example, simply trusting the pre-proven quadratic formula or the value of π (Pi).

RG2015

zagfles said:

RG2015 said:

AmityNeon said:

zagfles said:

AmityNeon said:

zagfles said:

AmityNeon said:

zagfles said:

AmityNeon said:

zagfles said:

There are other examples. Eg

x^2 = y^2.

So logically, x = y, right? Same operation both sides?

No, because the concept of a double negative is still logical. If I owe three people a negative debt of £3 each, it equally means three people each owe me £3. I can go up uphill forwards, or turn my body around and walk backwards (whilst still moving uphill).

That's certainly logical. But I was talking about the general "logical" principle of applying the same operation to both sides of the equation.

What about it? You must apply the same operation to both sides of an equation; that has no relation to forcing logic to somehow deduce that x = y.

OK, using your logic, work out the amount of energy your solar panels would generate on a sunny day. I guarantee you won't be able to do it without using calculus. If you can work out how to use calculus from first principles without being taught it or looking it up, I'll be mighty impressed!

I'm not sure what point you think I made for you to steer this conversation towards calculating the amount of energy solar panels can generate on a sunny day, or how that is relevant to applying the same operations to both sides of an equation to maintain logical consistency.

You seem to be under the impression I believe logic renders maths useless, or something. Logic is simply the basis of maths; you cannot study maths successfully without being a logical and critical thinker. You also don't need to like or study maths to use basic arithmetic and logic to understand personal finance at the consumer level.

Yes you do. That's the point. I've given enough examples where you really do need to have done some study of maths or at least have been taught or looked up mathematical techniques. Unless you really are Einstein and can work all these things out from first principles. How much energy your solar panels generate is a personal finance issue. To work it out, you need calculus. It's an extreme example, but other stuff like drawdown etc does need mathematical techniques which can be taught or looked up. There's no point reinventing the wheel.

I only have a GCSE in maths, which the vast majority of adults also have (or equivalent), and I managed to derive the Regular Saver formula for myself. I just remembered the basic arithmetic and algebra I was taught in school decades ago; I didn't look anything else up, and there was no calculator either. I am no Einstein or child prodigy, or even academically gifted. My career does not involve a related discipline. What I did have, was the attitude that I could probably do it.

Can you share this simple GCSE formula please. Apologies if you have already done this.  

Monthly saving x interest rate/100 x 6.5

So for the FD one 300 x 7/100 x 6.5 = 136.50

It can be different for other banks, eg Nationwide used calendar months, so you could open the account at the end of the month, make a deposit, then deposit again on the first of the next month, and make a total of 13 deposits. So it'd be a bit more with them. But they don't have a RS at the moment AFAIK.

Thank you, but this formula I know.

I was actually intrigued how @AmityNeon derived it (or any other pertinent formula) from the GCSE maths syllabus. 

AmityNeon

zagfles said:

AmityNeon said:

zagfles said:
You seem to be saying people don't need teaching maths or be shown mathematical techniques because they should be able to work it all out themselves.

Really? Where did I say that?

"It's not a case of they 'should' be able to solve everyday maths problems with innate logic; they can do it. "

Can do it (not 'should'); the context being adults are already educated in basic arithmetic and algebra due to compulsory maths education. Adults don't need additional study or to learn formal mathematical techniques (like geometric progression or calculus).

zagfles

OceanSound said:

zagfles said:

OceanSound said:

zagfles said:

OceanSound said:

zagfles said:

OceanSound said:

Albermarle said:

Basically if you have £3600 to save as a lump sum, you would be better just to put it a normal savings account for a one year fix. This FD account is more for people who are regular monthly savers.

Using the drip feed method where you deposit the £3600 in a current account like Kroo then drip feed the monthly payment of £300 in to First Direct Current Account then in to Regular Saver (RS) brings in a higher profit than saving it as a lump sum. 

I checked the moneyfacts website for the highest interest paying place for a 1 year Fixed deposit for £3600. It is Hampshire trust Bank paying 4.91%. So this would be ---> 3600 x 0.0491 = £176.76

However, if using the drip feed method. First Direct RS will pay £136.50 (source: https://www.firstdirect.com/savings-and-investments/savings/regular-saver-account/ ) notice though, if you scroll down the page under key product info it says:

• total deposit at the end of 12 months: £3,600....

• balance at the end of 12 months: £3,726.50

£3,726.50 - £3600  is £126.50. So there appears to be a discrepancy. 

Anyway if we use Kroo current account which pays 3.33%, then for the 12 months the interest works out to be  £58.29. I calculated this figure month by month. e.g. staring off with £3300 (because £300 of the £3600 will be paid in to FD to start with), then every month deducted £300 from the £3300 and worked out the interest every month for the 12 months then added the figures together. 

Now, we add £58.29 to £126.50 (interest from FD RS) and the combined total is £184.79 - which is more than the profit from the 1 year fixed rate. Note this is using the FD RS interest of £126.50 not £136.50. If we use the latter, the profit will be even more. 

BTW, I've a spreadsheet where I use this formula:

=SUM(12*E10)*C10/12*6.5

to calculate the interest from a regular saver. When I plug in the values. i.e. the interest divided by 100 (in this case 0.07) and the monthly deposit amount (in this case 300), it gives me a result of 136.50. 

As another check I then visit: https://www.moneysavingexpert.com/savings/regular-savings-calculator/

and plug in the values, and the result is £135. So, the £136.50 or £135 figure seems correct, not the £126.50. Probably a typo, and the 'balance at the end of 12 months: ' should state £3,736.50.

It'll vary a bit due to different month lengths, weekends etc. £136.50 assumes equal length months and payments going in one the same date every month.

It won't vary by exactly £10 due to different month lengths, weekends etc. 

Btw, I'm presuming you are referring to the discrepancy between £136.50 and £126.50, as your reply didn't say you are referring to the difference between FD RS website (including my spreadsheet formula) £136.50 and MSE website £135.00.

No probably less than £1 or so, just making the point the figure won't be exact.

Oh! I see. So, the FD website £10 discrepancy is a typo?

Probably, or maybe a worst case scenario, although £10 seems a bit high.

Really? Several bank holidays. E.g. due to coronation and ...<scratching my head now>

Edit: worse case scenario has magically or by coincidence come up with a £10 difference?

On that webpage it tells us the assumptions. If FD used different assumptions to work out a 'worse case' scenario, FD would need to make us aware!

Yeah £10 is far too high, it'll be a typo. If any £300 goes in a day late due to weekemnd/bank hols it'll cost about 5.7p in interest, realistically most months it won't go in day late, some months one or two days late, maybe 3 or even 4 very occasionally with bank hols, but overall over a year it will be handful, no more than 10 or so anyway, so it'll cost less than £1 in interest. Variable months may cost a little but again unlikely to be more than pence, so £10 is definitely not right, it'll be a typo.

AmityNeon

RG2015 said:

I was actually intrigued how @AmityNeon derived it (or any other pertinent formula) from the GCSE maths syllabus.

mrn(n+1)/24 + m(r+x)(12-n)(12-n+1)/24 + m(r-y)n(12-n)/12 > mr6.5

We're familiar with m * r * 6.5, which is based on consecutively adding incremental monthly interest contributions (up to month 12). It represents the last part (right side) of the formula, of which the left side needs to be greater than the right, in order for closing/renewing our RS to be considered worthwhile.

For the left side, we need a similar formula but for a variable number of months, n.

• 1 month + 2 months + 3 months + 4 months + 5 months...
• = 1 + 2 + 3 + 4 + 5...
• = 1, 3, 6, 10, 15...

The formula for finding the value for the nth month is n(n + 1) / 2. You can visualise this intuitively like a triangle being doubled to a rectangle:

n o o o o o
n n o o o o
n n n o o o
n n n n o o
n n n n n o

In the fifth month, there are five rows of n, and inversely there are also five rows of o, but it's a rectangle as there are n + 1 columns. So however many months we've held our RS for, the formula n(n + 1) / 2 calculates how many monthly contributions of interest we've accrued. At 12 months: 12 * 13 / 2 = 78.

We know interest is calculated daily, but we approximate using monthly interest, so the annual interest rate is divided by 12. 78 monthly contributions earning 1/12 of the annual interest rate = m * (r / 12) * 78 = m * r * 6.5.

The two formulas are then merged. Instead of calculating 78, we leave the formula for n as it is, because the number of months we've held our RS for is variable (and less than 12 for this purpose).

m * (r / 12) * n(n + 1) / 2

mrn(n + 1) / 24

Dividing by 2 and then dividing by 12 is the same as dividing by 24.

So that's the first part of the left side figured out; it calculates the amount of interest accrued in our current RS. Then we close/renew...

When we restart our RS, we calculate its length up to the end of month 12 of the old RS. So if we closed our old RS at 5 months, we need to calculate the amount of interest accrued in the new RS for 7 months. This ensures that the total amount of monthly contributions earning interest on both sides of the formula is equal to 78 over 12 months (for a fair mathematical comparison).

n
n n
n n n
n n n n
n n n n n

e e e e e   S
e e e e e   S S
e e e e e   S S S
e e e e e   S S S S
e e e e e   S S S S S
e e e e e   S S S S S S
e e e e e   S S S S S S S

We can see that the 78 monthly contributions consist of three parts:

• The original 5 months, represented by the upper n triangle.
• The next 7 months, represented by the lower-right S triangle.
• The 'excess' 5 months of contributions moved into an easy-access saver, represented by the e rectangle.

We already know the formula to calculate interest over a variable number of months: mrn(n+1)/24

What's different about the S triangle? It has an increased rate of interest, so we use r + x, where x is the increase over r. The number of months is also 12 - n. We plug those values in to achieve the middle part of the left side:

m(r + x)(12 - n)(12 - n + 1) / 24

Calculating the interest for the e rectangle means we do not divide by 24, but by 12. We can visually see the dimensions of the rectangle: n * (12 - n). The reduced rate of interest is expressed as r - y. This achieves the last part of the left side and completes the formula:

m(r - y)n(12 - n) / 12

Part 1            Part 2                        Part 3
mrn(n+1)/24   +   m(r+x)(12-n)(12-n+1)/24   +   m(r-y)n(12-n)/12   >   mr6.5

The full formula can be entered into a spreadsheet for easy calculation.

It can be simplified if desired to the variants below, but that requires a stronger grasp of expanding, factoring and rearranging.

m * ((n − 12) * ((n − 13) * x + (2 * n * y)) + (156 * r)) / 24 > mr6.5

We can eliminate m and r as they're both constant on both sides of the comparison (although we lose actual interest figures as a result):

(n − 12) * ((n − 13) * x + (2 * n * y)) > 0

metrobus

Total wind merchant

retiringtoosoon

zagfles said:

retiringtoosoon said:

zagfles said:

AmityNeon said:

zagfles said:

Beddie said:

Millyonare said:

The UK should really make all pupils 14-16yo do a GCSE in Arithmetic -- and not leave school until they achieve grade 4 / C or better.

For the vast majority of employees and employers, simple arithmetic is all the maths they will mostly ever need to use in work or home or for personal finances.

Mandatory GCSE Arithmetic would noticeably improve UK productivity.

I get your point, but not everyone is capable of being good at arithmetic. In the same way I cannot draw or paint, others cannot work with numbers. And just forcing them will put them off for life. There should be plenty of encouraging, yes, and also schools should do realistic scenarios e.g. wages, tax, renting, buying a house etc. instead of the "dry" maths mostly taught. Have it as a project, not just a lesson.

Yes, stuff like algebra is a good example. It can be used for all sorts of useful things, I've just used it to work out how much I should be spending on my Barclaycard to get best value from the balance transfer I've just done. But most people just learn it at school then forget about it because they don't see the practical use for it, because it was never taught in the context of real life scenarios.

Basic algebra is wonderfully applicable as it only requires logic. Recently we wanted to determine whether it was worth 'renewing' LBG Regular Savers to their higher rates, which resulted in generic formulas. Simplifying can take a bit of arithmetic training and perhaps an affinity for numbers, but simplifying isn't strictly necessary with calculators doing the heavy lifting.

Not sure about only logic, you do need a bit of arithmetric training. Rearranging an equation is usually as hard or harder than "simplifying", and you can't use a (normal) calculator for that, and you do need to rearrange when the value you're resolving for is on both sides of the equation. That doesn't seem to be the case with your regular saver formula, so although it looks complicated it is probably simpler in that the value you are calculating is only on one side of the formula, so no rearranging is necessary.

The Barclaycard one is a fairly simple example of what I'm talking about. The idea is I want best value from the balance transfer I've done. Normally with balance transfers you pay min payment every month which reduces the amount you're getting at 0% every month, so you don't get full value of the interest free credit on the whole amount for the whole period.

But with Barclaycard, you can spend and if that spending is paid off then no interest is charged on the spending (not the case with some other cards).

Min payment is 2.25% of the total of spending and balance transfer. So you need to spend enough so that 2.25% of the spending plus balance transfer equals the spending. So spending is on both sides of the formula, and spending is what you want to know.

So eg I've done a balance transfer (inc fee) of £5000. How much do I need to spend? If s is spend then

(5000+s)*0.0225=s

5000*0.0225 + 0.0225s = s

5000*0.0225 = s(1-0.0225)

s = 5000*0.0225/(1-0.0225)

s = 115.09

Confirm that 5115.09 * 0.0225 = 115.09

Booooooorrrrrring!

See that's the problem with some people and maths, as touched on earlier. Maths is seen as boring, being bad at maths is like a badge of honour, "I'm not a boring geek". They think it makes them look more interesting.

So even on page 8 of a thread discussing technical details of interest calculation, on a site called "moneysavingexpert" where the technicalities of saving money are (or should be) the main topic of discussion, someone feels the need to call a bit of simple algebra used to illustrate a point "boring".

Loads of threads here and other places go in depth on details on all sorts of stuff most people would find boring, but not many people feel the need to post "Booooooorrrrrring". But maths seems to be an exception...perhaps along with trainspotting where people seem to enjoy making others feel a freak for being interested in something most people would find boring.

Anyway, I don't care if I've bored anyone. Move along, go read a more interesting site. I like maths and put it to practical use all the time, the only reason I can afford to retire early is a good understanding of finance and maths, and I will discuss it here even if some people find it boring.

Feel free to reply with a Tw*tter style one liner which you think makes you sound interesting.

Hey, I’ve got a masters degree in maths and physics. It’s still boooooorrring 😝

OceanSound

retiringtoosoon said:

zagfles said:

retiringtoosoon said:

zagfles said:

AmityNeon said:

zagfles said:

Beddie said:

Millyonare said:

The UK should really make all pupils 14-16yo do a GCSE in Arithmetic -- and not leave school until they achieve grade 4 / C or better.

For the vast majority of employees and employers, simple arithmetic is all the maths they will mostly ever need to use in work or home or for personal finances.

Mandatory GCSE Arithmetic would noticeably improve UK productivity.

I get your point, but not everyone is capable of being good at arithmetic. In the same way I cannot draw or paint, others cannot work with numbers. And just forcing them will put them off for life. There should be plenty of encouraging, yes, and also schools should do realistic scenarios e.g. wages, tax, renting, buying a house etc. instead of the "dry" maths mostly taught. Have it as a project, not just a lesson.

Yes, stuff like algebra is a good example. It can be used for all sorts of useful things, I've just used it to work out how much I should be spending on my Barclaycard to get best value from the balance transfer I've just done. But most people just learn it at school then forget about it because they don't see the practical use for it, because it was never taught in the context of real life scenarios.

Basic algebra is wonderfully applicable as it only requires logic. Recently we wanted to determine whether it was worth 'renewing' LBG Regular Savers to their higher rates, which resulted in generic formulas. Simplifying can take a bit of arithmetic training and perhaps an affinity for numbers, but simplifying isn't strictly necessary with calculators doing the heavy lifting.

Not sure about only logic, you do need a bit of arithmetric training. Rearranging an equation is usually as hard or harder than "simplifying", and you can't use a (normal) calculator for that, and you do need to rearrange when the value you're resolving for is on both sides of the equation. That doesn't seem to be the case with your regular saver formula, so although it looks complicated it is probably simpler in that the value you are calculating is only on one side of the formula, so no rearranging is necessary.

The Barclaycard one is a fairly simple example of what I'm talking about. The idea is I want best value from the balance transfer I've done. Normally with balance transfers you pay min payment every month which reduces the amount you're getting at 0% every month, so you don't get full value of the interest free credit on the whole amount for the whole period.

But with Barclaycard, you can spend and if that spending is paid off then no interest is charged on the spending (not the case with some other cards).

Min payment is 2.25% of the total of spending and balance transfer. So you need to spend enough so that 2.25% of the spending plus balance transfer equals the spending. So spending is on both sides of the formula, and spending is what you want to know.

So eg I've done a balance transfer (inc fee) of £5000. How much do I need to spend? If s is spend then

(5000+s)*0.0225=s

5000*0.0225 + 0.0225s = s

5000*0.0225 = s(1-0.0225)

s = 5000*0.0225/(1-0.0225)

s = 115.09

Confirm that 5115.09 * 0.0225 = 115.09

Booooooorrrrrring!

See that's the problem with some people and maths, as touched on earlier. Maths is seen as boring, being bad at maths is like a badge of honour, "I'm not a boring geek". They think it makes them look more interesting.

So even on page 8 of a thread discussing technical details of interest calculation, on a site called "moneysavingexpert" where the technicalities of saving money are (or should be) the main topic of discussion, someone feels the need to call a bit of simple algebra used to illustrate a point "boring".

Loads of threads here and other places go in depth on details on all sorts of stuff most people would find boring, but not many people feel the need to post "Booooooorrrrrring". But maths seems to be an exception...perhaps along with trainspotting where people seem to enjoy making others feel a freak for being interested in something most people would find boring.

Anyway, I don't care if I've bored anyone. Move along, go read a more interesting site. I like maths and put it to practical use all the time, the only reason I can afford to retire early is a good understanding of finance and maths, and I will discuss it here even if some people find it boring.

Feel free to reply with a Tw*tter style one liner which you think makes you sound interesting.

Hey, I’ve got a masters degree in maths and physics. It’s still boooooorrring 😝

How do I access the post you're replying to in order to give them thanks - other than going through each and every page? (which I don't particularly mind had I not been through every page already. Going through them for the umpteenth time every time a forumite replies and I want to see the original post they are replying to is boooooooring!)