You have the current volume of sales and percent change vs a year ago but you need to calculate the year ago volume is there a formula or macro to get this done?

Answer 1

If I get this right you know the volume of sales for this year and know the percentage that it changed since last year and need to know the volume of last year?

First, you need to know what percent of last years volume that this years volume is, if not ...

let's say it increased by x% then this year the volume is 100+x% of last year or

if it decreased by x% then this years volume is (100-x)% of last year

Second,

volume this year = percentage change* last years volume

percentage means per 100 and "of" means multiply

so for example if this year the volume is 150 and it increased by 50%

then your percentage of last year is 150

150 = 150/100 * last years volume

150 = 1.5 * last years volume

150/1.5 = last years volume

100 = last years volume

Hope this helps..