Unit 1 - Compound Interest

Compound interest is when the interest is added on each year.
The formula used to work out compound interest is:

Where, P = the principle ammount (the amount invested),

and N = number of years.

Example:
£900 was placed in the bank for 2 years, at an interest rate of 4% p.a.
What was the total interest made after the 2 years??