I'm crap at basic maths - help me please !!

[GuildfordPaul]

So, I start with a figure of 71.45 and deduct 10.17% = 64.18.

From 64.18 how do I get back to 71.45, if I add 10.17% it doesn't work, if I multiply by 10.17% it doesn't work, is there a simple reverse formula to use?

[johnfm]

divide by (1-.1017)

[fido]

GuildfordPaul said:

So, I start with a figure of 71.45 and deduct 10.17% = 64.18.

From 64.18 how do I get back to 71.45, if I add 10.17% it doesn't work, if I multiply by 10.17% it doesn't work, is there a simple reverse formula to use?

FFS.

64.18 * 1 / (1 - 0.1017) = 71.45

[ol]

10.17% of 71.45 is different to 10.17% of 64.18 so you cant just subtract a % and then add the same % and come back to the same figure.

Edited by ol on Wednesday 15th October 13:57

[Mc Lovin]

use a calculator

[lunarscope]

GuildfordPaul said:

So, I start with a figure of 71.45 and deduct 10.17% = 64.18.

From 64.18 how do I get back to 71.45, if I add 10.17% it doesn't work, if I multiply by 10.17% it doesn't work, is there a simple reverse formula to use?

71.45 / 64.18 = 1.1132751636
64.18 * 1.1132751636 = 71.45

[GuildfordPaul]

brackets and slashes no help me, please explain what buttons to press on calculator... ta

[GuildfordPaul]

Mc Lovin said:

use a calculator

i've tried!!

[Scott328i]

x = 100%

x / 100 = y

y x z = final figure

z = 89.83 = 100 - 10.17


This is for simpletons may I add

Edited by Scott328i on Wednesday 15th October 14:00

[johnfm]

I am shocked. How have you managed to get by in life so far??

[Vee]

GuildfordPaul said:

So, I start with a figure of 71.45 and deduct 10.17% = 64.18.

From 64.18 how do I get back to 71.45, if I add 10.17% it doesn't work, if I multiply by 10.17% it doesn't work, is there a simple reverse formula to use?

You calculated 89.83% of 71.45
To get back to the whole value you must divide by 89.83%

[GuildfordPaul]

johnfm said:

I am shocked. How have you managed to get by in life so far??

by asking people when i get stuck

[esselte]

GuildfordPaul said:

johnfm said:

I am shocked. How have you managed to get by in life so far??

by asking people when i get stuck

How do you know they're telling the truth when they answer?

[Steamer]

esselte said:

GuildfordPaul said:

johnfm said:

I am shocked. How have you managed to get by in life so far??

by asking people when i get stuck

How do you know they're telling the truth when they answer?

It doesnt matter - you then blame them when it all goes tits up! Point the finger and keep on moving up that ladder!

[emicen]

What is actually scarey about this is, I bet a huge number of people with credit cards at x%, loans at y% and mortgages at z% would be buggered by having to do exactly the same calculations!

[scruffy]

GuildfordPaul said:

So, I start with a figure of 71.45 and deduct 10.17% = 64.18.

From 64.18 how do I get back to 71.45, if I add 10.17% it doesn't work, if I multiply by 10.17% it doesn't work, is there a simple reverse formula to use?

If your cake weighs 71.45 kgs (big cake!) and you cut 10.17% off it you're left with a smaller bit. 64.18 Kgs. 10% of 64.18 is a smaller piece than 10% of 71.45.

Wait, is this Euclidean Comohology or Non-Hamiltonian Geometry...

[GuildfordPaul]

lunarscope said:

GuildfordPaul said:

So, I start with a figure of 71.45 and deduct 10.17% = 64.18.

From 64.18 how do I get back to 71.45, if I add 10.17% it doesn't work, if I multiply by 10.17% it doesn't work, is there a simple reverse formula to use?

71.45 / 64.18 = 1.1132751636
64.18 * 1.1132751636 = 71.45

i like this one best, and it works with all the figures i'm using, ta very muchly!

[4hero]

not sure about your sum, but if you do:

22 men in a 5* hotel, drank 88 pints of beer in 67 seconds. Multiply the numbers (2258867) by 2 and turn the calculator upside down it'll give you an idea of how they felt in the morning

[Mc Lovin]

GuildfordPaul said:

johnfm said:

I am shocked. How have you managed to get by in life so far??

by asking people when i get stuck

I am a lot worse than you are by the looks of things, i've got by somehow, luck mostly

[speedy_thrills]

Vee said:

GuildfordPaul said:

So, I start with a figure of 71.45 and deduct 10.17% = 64.18.

From 64.18 how do I get back to 71.45, if I add 10.17% it doesn't work, if I multiply by 10.17% it doesn't work, is there a simple reverse formula to use?

You calculated 89.83% of 71.45
To get back to the whole value you must divide by 89.83%

So 71.45 times .8983 (this number comes from dividing 89.83 by 100 before you start) = 64.18 (approx.)
64.18 divided by .8983 = 71.45 (approx.)

Does that help? It's just about the simplest logical way.