What is the best math formula for finding compounded intrest and at what percent a principle was compounded?

Question

I am really bad at math and, need a little help simple answers please

Answer 1

This one is pretty simple:

F = P (1 + i)^n

where: F = final value; P = present value; i = interest rate per compounding period; n = number of compounding periods

To find the interest (and just the interest), that's F - P

To find the percent at which it was compounded...

i = (F/P)^(1/n) - 1