 Compound interest has often been referred to as the eighth wonder of the world.

## What is compound interest?

When you save or invest the return on your money is known as the interest. Compound interest is the money you make on that interest. It is the interest on interest.

The longer you save or invest the more interest you can make on your interest.

Think of it like a snowball. You start with a small snowball at the top of a hill and as it goes down the hill it picks up more snow. By the bottom of the hill the snowball is a lot bigger.

The bigger the hill, the bigger the snowball at the bottom of the hill. The longer your investment time, the bigger your investment could be at the end.

## Compound Interest Example

Imagine you saved £5 a week which is £260 a year. In 40 years you would have saved £10,400.

If you invested that £260 a year at annual rate of 10% you would have £115,074 after 40 years. Thanks to the power of compounding you would have 10 times the amount of money.

After 40 years you would still be earning 10% interest on your money which would be £11,507. You would make more interest in year than the total amount you invested over the 40 years. Amazing isn’t it!?

## How do you calculate compound interest?

The Rule of 72 is a simple trick to work out how long it will take for you to double your money.

Divide the number 72 by the interest rate. For example, if your money grew at 8% (72/8 = 9), it would take 9 years to double your money.

The mathematical equation for interest being compounded once a year is A = P(1 + r)n

Total (A) = initial Investment (P) x (1+ interest rate (r)) by time (n) squared