Calculation bug

************EDIT
please delete this question.
it is not a bug.

https://i.imgur.com/9tW4Jce.jpg

If Characters by user is 43688
and characters added by sql assistant is 590725

so productivity gain according to the software is : 590725/43688 = 13.52 * 100 = 1352 %

But that is incorrect:

if a dress costs 100$ and now it is 250$ so the addition of price is not : 250/100 *100 = 250 % . it is (250/100 -1 )*100 which is 150%. so 150% addition to the base which is 100 IS 250 $

So it should be : (590725/43688 - 1 ) * 100 which is 1252%