Also i just want to add something else you said which either i misunderstood or James missed.
For your newest example did you want to add 10% interest AND an extra $10 each week?
shouldn't be 10 instead of 1,000?
sorry it is not my first language
i meant 10$ and 10% raise each week
aka 1st week 10$
2nd week 11$
etc
1'000 is the Initial Amount ...
10% is the WEEKLY interest rate
52 is the Number of Weeks ...
I proposed the mathematical formula ... to give you an opportunity to understand the underlying logic ...
If you only need to use Excel built-in functions ... as shown by Ahoync ... with FV ... you are getting the same results ...
If you mean 10 ... when you type 1'000 ...
.
=C1*A1+(C1-1)*((1+(C1-1))/2)*(A1*B1)