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# Help with how much my appliance costs?

• Posts: 1,348 Forumite
Gerry1 said:
HuCliveOfIndia said:
Krakkkers said:

Could you link to any LED Christmas tree lights (300 or less) that would use more than 32p a day based on a 0.27p per kwh charge?
You are doing it again, you pay 27p per kwh not 0.27p
So why is it written with that decimal point where it is?
£0.27 is 27p.
£1.27 is one pound 27p surely?

As the poster above says, a number can't have two decimal points?
As a slight aside, you say "a number can't have two decimal points".  It can, just look at any petrol forecourt, petrol is 153.7 pence per litre or whatever.  So you can't actually buy exactly 1 litre of petrol, even though it's priced at so much per litre.  Always seems daft to me !
Maybe I need to go to Specsavers: I can see only one decimal point in 153.7 pence. 🤓

OK, fair enough, that was just to illustrate the fact that "pounds and pence" can be expressed in decimals which don't exist in the real world for all practical purposes, as far as Joe Public is concerned.

Gerry1 said:

A quantity cannot have two decimal points !
Of course it can.  A quantity can have any number of decimal places.  Buy a bunch of bananas at Tesco, it's weighed and the price calculated at "so-much-per-kilogram", usually to 2 decimal places.  Buy your electricity, you can easily use.127.75 KWH.  They may "round up or down" to 2 decimal places for ease of billing, but of course it's possible to use/pay for "2 decimal places of the unit price".

Whether it's realistic or practical to express it as such in everyday life is arguable - nuclear physicists probably express quantities down to many, many decimal places all the time due to necessity, but your average Joe Public buying apples or petrol or gas or electricity doesn't need such a level of accuracy.
The big oil companies probably (I don't know for sure) do go down to 3 or 4 or maybe even 5 decimal places when trading, but then you're into the realms of multi-billion-dollar deals where a small difference in price can make a big difference in profit/loss.

• Posts: 2,147 Forumite
It's a carp App for an energy monitor smart plug probably.

My Meross smart plugs show:
>>> for one string of 200 led lights with a transformer wall wart (not switched mode so more energy hungry) Current Power: 21.76 Watts. Energy used today 0.031 kWh (31 Wh) and 0.165 kWh/day on average.
>>> for another string of 100 leds, nominally 6 Watts it shows: Current 5.31 Watts, 0.021 kWh today and an average of 0.043 kWh per day.
They are on timers, so not on all day long.

Both sets are around 1/5 th of a kWh per day which at my 28p per unit is less than 6 pence.

My 2200 Watt kettle will consume more energy in 6 minutes of operation.  That's probably less than two pots of tea for the two of us,  We drink more than that every day .  Then put the induction hob, grill or oven on, washer or dryer...  Modern led Fairy lights are well down in the noise for electric use!!

• Posts: 9,936 Forumite
CliveOfIndia said:

Gerry1 said:

A quantity cannot have two decimal points !
Of course it can.  A quantity can have any number of decimal places.  Buy a bunch of bananas at Tesco, it's weighed and the price calculated at "so-much-per-kilogram", usually to 2 decimal places.  Buy your electricity, you can easily use.127.75 KWH.  They may "round up or down" to 2 decimal places for ease of billing, but of course it's possible to use/pay for "2 decimal places of the unit price".

@CliveOfIndia Decimal POINTS are completely different to decimal PLACES !
Gerry1 said:
CliveOfIndia said:

Gerry1 said:

A quantity cannot have two decimal points !
Of course it can.  A quantity can have any number of decimal places.  Buy a bunch of bananas at Tesco, it's weighed and the price calculated at "so-much-per-kilogram", usually to 2 decimal places.  Buy your electricity, you can easily use.127.75 KWH.  They may "round up or down" to 2 decimal places for ease of billing, but of course it's possible to use/pay for "2 decimal places of the unit price".

@CliveOfIndia Decimal POINTS are completely different to decimal PLACES !

Time and again we see kW and kWh misunderstood. Throw misrepresenting decimal coinage into the mix and total confusion rules. Much to be said for good old pounds, shillings, and pence. Not to mention ha'pennies and farthings!

I’m a Forum Ambassador and I support the Forum Team on the In My Home MoneySaving, Energy and Techie Stuff boards. If you need any help on these boards, do let me know. Please note that Ambassadors are not moderators. Any posts you spot in breach of the Forum Rules should be reported via the report button, or by emailing forumteam@moneysavingexpert.com.

All views are my own and not the official line of MoneySavingExpert.

• Posts: 9,936 Forumite
victor2 said:
Gerry1 said:
CliveOfIndia said:

Gerry1 said:

A quantity cannot have two decimal points !
Of course it can.  A quantity can have any number of decimal places.  Buy a bunch of bananas at Tesco, it's weighed and the price calculated at "so-much-per-kilogram", usually to 2 decimal places.  Buy your electricity, you can easily use.127.75 KWH.  They may "round up or down" to 2 decimal places for ease of billing, but of course it's possible to use/pay for "2 decimal places of the unit price".

@CliveOfIndia Decimal POINTS are completely different to decimal PLACES !

Time and again we see kW and kWh misunderstood. Throw misrepresenting decimal coinage into the mix and total confusion rules. Much to be said for good old pounds, shillings, and pence. Not to mention ha'pennies and farthings!
The annual standing charges with Gerry1Energy will total 119½ Guineas...
• Posts: 11,857 Forumite
Gerry1 said:
victor2 said:
Gerry1 said:
CliveOfIndia said:

Gerry1 said:

A quantity cannot have two decimal points !
Of course it can.  A quantity can have any number of decimal places.  Buy a bunch of bananas at Tesco, it's weighed and the price calculated at "so-much-per-kilogram", usually to 2 decimal places.  Buy your electricity, you can easily use.127.75 KWH.  They may "round up or down" to 2 decimal places for ease of billing, but of course it's possible to use/pay for "2 decimal places of the unit price".

@CliveOfIndia Decimal POINTS are completely different to decimal PLACES !

Time and again we see kW and kWh misunderstood. Throw misrepresenting decimal coinage into the mix and total confusion rules. Much to be said for good old pounds, shillings, and pence. Not to mention ha'pennies and farthings!
The annual standing charges with Gerry1Energy will total 119½ Guineas...
The annual charges with DCMenergy will total 12pints of Guiness🍺
🍺 😎 Still grumpy, and No, Cloudflare I am NOT a robot 🤖BUT my responses are now out of my control they are posted via ChatGPT or the latest AI
• Posts: 9,936 Forumite
Gerry1 said:
victor2 said:
Gerry1 said:
CliveOfIndia said:

Gerry1 said:

A quantity cannot have two decimal points !
Of course it can.  A quantity can have any number of decimal places.  Buy a bunch of bananas at Tesco, it's weighed and the price calculated at "so-much-per-kilogram", usually to 2 decimal places.  Buy your electricity, you can easily use.127.75 KWH.  They may "round up or down" to 2 decimal places for ease of billing, but of course it's possible to use/pay for "2 decimal places of the unit price".

@CliveOfIndia Decimal POINTS are completely different to decimal PLACES !

Time and again we see kW and kWh misunderstood. Throw misrepresenting decimal coinage into the mix and total confusion rules. Much to be said for good old pounds, shillings, and pence. Not to mention ha'pennies and farthings!
The annual standing charges with Gerry1Energy will total 119½ Guineas...
The annual charges with DCMenergy will total 12pints of Guiness🍺
Nah, wouldn't work properly, the electrons would be like the bubbles and all flow the wrong way, making the meter go bac...
Oh, wait !

• Posts: 82 Forumite
Here is a phot from the app:

This is a lamp with an LED bulb in it.
Today it has used 0.01 units of electric.

If I pay £0.27 per 1.00 units of electricity, then today it's used £0.27 (27p - surely not as it hasn't used 1.00kwh?) or £0.02 - 2p?
How long was this lamp on for on this day? If it was about 2 hours then you have a 5w lamp (0.005kw), and if it was on for just 12 minutes you have a 50w (0.05kw) lamp. This of course assumes the lamp is on constantly at full brightness. If your electric cost is 27p/kWh then the 0.01 units the lamp used is £0.0027 or 0.27p.

So the 5w lamp would cost £0.00135 (0.135p) per hour to run and the 50w lamp would be £0.0135 (1.35p).
Based on writing money like this (the way I was taught in school?):

£100.00 is one hundred pounds and no pence
£100.50 is one hundred pounds and fifty pence
£34.10 is thirty four pounds and ten pence
£1.04 is one pound and four pence

I understand petrol goes into 10th of pences, but they don't really exist - nobody goes into the petrol station to claim the tiny amount back.

I think this is why I don't understand what 0.135p is.  No pounds and thirteen and a half pence?  No pounds and one hundred and thirty five pence?  I have always been taught in this scale of numbers, anything before a decimal point is a pound and anything after is a pence (until you get to much bigger values of course).

So when someone writes 1.35p, I only understand it's £1.35 albeit written weirdly.  If it's all pence, why isn't it £0.135 (which is then understandable as zero pounds, thirteen and a half pence?).

If I kept the lamp on for weeks, months and it racked up ten pounds of cost, how would you write that when using 1.35p as a base?  Because 10.1.35p isn't a value number that anyone sane would understand :P
@TractorFactor, your education presumably gave you an understanding of what 0.5p means, even if we don't have half pennies any more.
So, 10 of them would be 5p, or £0.05.
At the other end of the scale, £1 million is easier to read than £1,000,000.
Not difficult to understand, surely?

I’m a Forum Ambassador and I support the Forum Team on the In My Home MoneySaving, Energy and Techie Stuff boards. If you need any help on these boards, do let me know. Please note that Ambassadors are not moderators. Any posts you spot in breach of the Forum Rules should be reported via the report button, or by emailing forumteam@moneysavingexpert.com.

All views are my own and not the official line of MoneySavingExpert.

• Posts: 13,822 Forumite
I think this is why I don't understand what 0.135p is.  No pounds and thirteen and a half pence?  No pounds and one hundred and thirty five pence?
One hundred-and-thirty-five one-thousandths of a penny. Or, one-tenth of a penny plus three-hundredths of a penny plus five one-thousandths of a penny.
Or just less than one-seventh of a penny, if you prefer fractions to decimals.
I have always been taught in this scale of numbers, anything before a decimal point is a pound and anything after is a pence (until you get to much bigger values of course).
Anything before the decimal point is a whole unit, anything after the point is a fractional unit. With currency you can talk about pounds and pence but with miles / gallons / seconds you don't.
So when someone writes 1.35p, I only understand it's £1.35 albeit written weirdly.  If it's all pence, why isn't it £0.135 (which is then understandable as zero pounds, thirteen and a half pence?).
1.35p is one penny plus thirty-five hundredths of a penny. It's one-hundredth of £1.35. If written as pounds, it would be £0.0135.
If I kept the lamp on for weeks, months and it racked up ten pounds of cost, how would you write that when using 1.35p as a base?  Because 10.1.35p isn't a value number that anyone sane would understand :P
You'd write ten pounds as £10, or (if you felt the need) as 1000p.
N. Hampshire, he/him. Octopus Go elec & Tracker gas / Shell BB / Lyca mobi. Ripple Kirk Hill member.
2.72kWp PV facing SSW installed Jan 2012. 11 x 247w panels, 3.6kw inverter. 30MWh generated, long-term average 2.6 Os.
Taking a break, hope to be back eventually.
Ofgem cap table, Ofgem cap explainer. Economy 7 cap explainer. Gas vs E7 vs peak elec heating costs.

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