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

brightonman123

%ages justa number divied by 100.. not rocket science..

kalimai

Would have voted D. If shopping ask my husband, if he isn't around use the calculator and multiply by point whatever (i.e. £16.99 x 0.3 = discount). If no calculator I'm suffed, no maths made any sense until you put letters into it. Algebraic long division was the first time I ever understood division, hence I studied English!

neilvm

Why do 30% and then subtract the answer from the original number? Why not do 70% and you have your final answer in one go. All you do is do the same calculation but with 7 instead of 3. Divide the rounded up £17.00 by 10 giving 1.7 and then multiply by 7 giving 4.9+7 =£11.9 - result! You miss out a subtraction process where you can make a mistake.

julie777

:beer:

I was surprised at the high percentages of people who could manage this mental arithmetic, but then any one using this site is far more intelligent than the rest of the public anyway! LOL.

brightonman123

neilvm, sounds like too much hard work! 30% is just under a 1/3..

geebeeone

Call it £17 then multiply by 3 and you get 51 =£5.10

trickypockets

I can usually do percentages OK, but sometimes have trouble getting the decimal point in the right place if the amounts are large.
For some reason I had a eureka moment the other day when working out lots of 2% credit charges: I suddenly realised that one way of looking at it is to say that x% of any number of pounds is the same number of pence multiplied by x .

In other words :
2% of £17 is 17p x 2 = 34p
17% of £29 is 29p x 17 = 493p
43% of £19.50 is 19.5p x 43 = 838.5p

I don't know why, but it just seems easier to get it right if I think of it like this - previously I might have put 2% of £17 down as £3.40.

tomstickland

30% off £16.99

that's 3/10ths of 16.99
so 3 x 1.70 ish
which is £5.10ish

tomstickland

Eco_Miser wrote: »

A lot of people are saying to get 30%, divide by 10 then multiply by 3. Often multiply by 3 then divide by 10 is easier

It shouldn't make any difference, just a decimal point moved.

elisebutt65

I used to work in a busy London pub back in the 80's before they had tills that you entered the drinks into - you had to add up everything in your head and work out the change and at Xmas, we'd get huge parties ordering rounds of 25+ sometimes - doubles, cocktails, with mixers etc. Soon got used to mental arithmetic!!:rotfl:

Percentages are a piece of cake once you get used to it. Now I'm teaching, I rarely remember to bring a calculator so end up doing break even calculations etc on the whiteboard in front of the students and usually get the answer before the students have finished tapping everything into theirs. It's just easier.Or of course - I get them to do it for me:D