% fraction problem

V

Vass

I've looked and searched and cannot find the formula to the following

I have a value to which a % has been deducted
I need the formula to put that value back

i.e. the fraction formula

If 17.5% has been removed from a value and the remained is £ 2.00
whats the formula to find the deducted amount from the gross figure
Obviously to add 17.5% back on would not work

I need this formula for various %'s

Many thanks
 
K

kkknie

Algebraicly:

New Value = Original Value - Original Value x Percent

grouping,

New Value = Original Value x (1 - Percent)

solve for original value,

Original Value = New Value / (1 - Percent)

So in your case:

Original Value = 2.0 / (1 - 0.17) = 2.409639
 
F

Fiona O'Grady

If you have a list of "Discounted values" (in this example, 2) and a list
of the % discount that was applied (in this case 17.5) then you could use
the following:

A B C
Discounted % Discount Original Value
Value
2 17.5 ==A2*100/(100-B2)

Where column B is formatted as "general".

If you want to format column B as a percentage, then the formula in C
becomes

=A2/(1-B2)

The formula in C can be copied down.

Fiona
 
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