How to calculate for bank fee subtracting from total

Question

I play a game where to withdraw funds from a bank, it takes a 1% fee. I'm trying to create a formula to account for that fee. The formula I created doesn't work because it takes 1% of the new total which is sometimes less than what I the amount I want to withdraw. Since it's only 1% it wouldn't normally mean much, but often amounts are in the hundreds of millions.

a = entered amount

x = my adjusted amount

y = systems further adjusted amount

z = final amount

x = a + (a * .01)

y = x + (x * .01)

z = y - (y * .01)

I need z and a to have the same value.

Answer 1

As I understand your rather complex examples, you want to withdraw EXACTLY 500,000,000 and that INCLUDES the 1% fee.

 

Therefore

 

500,000,000 = a + 0.01a

500,000,000 = 1.01a

495,049,505 = a

 

So to determine the amount you want to draw (to include the 1%) divide by 1.01

 

E.g., to withdraw EXACTLY 100, you request 99.00990099 (100 / 1.01)