Reverse Percentage Calculation

[dgavin]

I use this formula to calculate what 9 + 30% is

=SUM((9-1)*(1+(30/100)))+1

which gives 11.4

But how do I change the formula to calculate what the percentage difference is between 9 and 11.4. i.e resulting in 30%

Thanks

 

[Jonmo1]

1st, I think you need to re-evaluate this

I use this formula to calculate what 9 + 30% is

=SUM((9-1)*(1+(30/100)))+1

Unless I've missunderstood the purpose of your initial formula..
9 + (30% of 9) = 11.7 (not 11.4)

9 * 0.30 = 2.7
9 + 2.7 = 11.7


A more accurate formula for 9+30% is
=9*1.3
or
=9+(9*0.3)

 

[mane_uk]

Hi dgavin,

Adding to what jonmo1 mentioned is good to point that reverse percentage is not as straight as you mentioned.

* 30% of 11.7 is 3.51 so you wouldn't have 9 but 8.19.

Saying you have the 11.7 and know the final result is 9, to calculate the percentage of the difference would be something like:
=(9*100)/11.7)
this way you find out the percentage 9 is out of 11.7, which has a result of 76.92308% which then you take from 100% to find the percentage of the difference: 23.07692%

Cheers
mane_uk

 

[edvwvw]

Reverse percentage is straightforward

In the example that you have given 11.7 represents 130% of the initial value

11.7/1.3 = 9

edvwvw

 

[mane_uk]

edvwvw,

It might represent 130% (9 is 100% plus its 30% which is 2.7!!) but the percentage of the 2.7 difference between 11.7 and 9 is not 30%.

So if you need to calculate the difference based on apercentage the calculation is not straight forward as you are suggesting.

Cheers

 

[Expiry]

I use this formula to calculate what 9 + 30% is

=SUM((9-1)*(1+(30/100)))+1

which gives 11.4

But how do I change the formula to calculate what the percentage difference is between 9 and 11.4. i.e resulting in 30%

Thanks

How did you ever come up with that formula for working out percentage? I've never seen anything like it.

I don't understand the logic of starting your sum by subtracting 1 and then adding it back on again at the end. This is the reason you end up with 11.4 and not 11.7, because you're missing the 30% of that 1, which you've omitted from the calculation.