'Can you do percentages in your head?' poll discussion

MarcMarc

Is it no wonder that many people in Britain are confused when it comes to percentages all the time that certain political parties will have us believe that polling 38% constitutes a majority! :rotfl:

poor_country_girl

richardw wrote: »

My favourites are wrong maths in supermarkets, ie can of beans for 42p or 4 can multipack for £1.74, er no thanks.

I see this quite often, I am sure it is deliberate - I bet loads of people wouldn't even work it out and accept it is cheaper - or maybe we are paying for the extra packaging on multipack...hmmmm

nomoneytoday

MarcMarc wrote: »

Is it no wonder that many people in Britain are confused when it comes to percentages all the time that certain political parties will have us believe that polling 38% constitutes a majority! :rotfl:

Depends on how many contestants there are

MrsE_2

eileenfromplaistow wrote: »

Even my sister, who only got her GCSE (showing our age now!) on the second go, can do the mental maths. I am appalled when Tesco put up an enormous chart for their "10% or 20% off" clothes sales, listing prices before, discount and "you pay". Woolworths used to do the same.
My niece, by the way, was most impressed that my daughter could convert the dimensions of her kitchen floor to "number of packs required" of laminate flooring in B&Q - she thought everyone had to get the assistant to work it out for them!

They crack me up:rotfl::rotfl::rotfl::rotfl::rotfl::rotfl:

MrsE_2

KeithSheppard wrote: »

The sample question isn't maths, it's arithmetic. There's a real difference. I have a maths degree. I have used (eg.) calculus many time in adult life but mathematicians are notoriously bad at arithmetic.

I can manipulate the formulae and love algebra, but I cannot add up to save my life. That's what computers are for.

I just about struggled through the sample question by saying it's 17 pounds, as near as darn it, then multiplying 1.7 by three. That's about on the limit of my arithmetic powers.

I work in finance, my money maths is good, but the other stuff:eek::eek::eek::eek:

MrsE_2

teddyco wrote: »

The secret to doing percentages in your head is to break the percentage of the item into pieces, figure out the pieces that you know, and then add them back together in your mind.

30% of £16.99 is easier when you round it up to £17.00 and then take 10% of £17.00 = £1.70...........then multiply by 3 = £5.10
So an item in the store that is £17.00 @ 30% discount has a total price of approximately £11.90.

The other way is to break the amount into pieces rather than the percentage. So for example: I don't know what 30% of £17.00 off the top of my head, but I do indeed know what 30% of £10.00 is and that's £3.00. I also don't know what 30% of £7.00 is, but I do know that 30% of £1.00 is £.30 pence. So I take £.30 pence and multiply that by 7 to get £2.10. Then add the parts back together and that's £3.00 + £2.10 = £5.10.....now subtract that from the original price of £17.00 and the discounted price of the item is £11.90.

It's like riding a bike; If you have never done it before, then it seems difficult, but after you train your mind to do it, it's as easy as falling off a log.

Thats they way I did it, but I don't know why I don't just do 3 x 10% (or 3 x £1.70)

cheepnis

wildthing01 wrote: »

there are lots of people going about calculating 33% and 25% discounts in very long-winded ways. for 33% just divide total by 3, for 25%, divide by 4. for anything ending in 0, divide by 10 then times by the number in the tens column (e.g. for 40%, divide by 10, times by 4).

i can't do anything more complex than that (e.g. trying to work out VAT at 17.5%). i got an A in my gcse maths, but i was allowed a calculator for that!!!

@ wildthing01

if you can divide by 10 and divide by 2 then for VaT @ 17.5% you'll only need a biro :santa2:

• Bill = £100-00
• start with 10% = £ 10-00
• divide that by 2 = £ 5-00 (5%)
• divide that by 2 = £ 2-50 (2.5%)
• add them up = £117-50

Thebiguglyone

That's the way I did the VAT.

Sometimes ends up involving a bit of guesswork when I don't have a pen handy because my memory is terrible!!!

OrkneyStar

wildthing01 wrote: »

what?????????????

I love silly maths

John-the-Handyman

I don't necessarily agree with some of the ways mentioned. I find it's much easier to do this.....

To calculate the reduced amount. If the deduction is 30% (i.e.30 per hundred) then the remaining sum will be 70% of the price.(100-30) (or .7 if you prefer. i.e seven tenths. 70/100 is the same as 7/10 or .7/1) So you just have to multiply the amount by 7 then move the decimal point back one place. £16.99 times 7 = 118.93 Therefore you will pay £11.89
Simple.

To work out the VAT inclusive price on anything just multiply the initial figure by 1.175 To work out the VAT free price it follows therefore that you just have to divide the VAT inclusive price by 1.175 Saves all the adding or subtracting bits or sums. Does it all in one go!

Life is as easy or as difficult as you make it.... I think.. i think I think... I'm sure I think I think. Well-perhaps. Oh I dunno......!:j