Joey opened a bank account 5 years ago with $100. today he has $1000 in the account. what is the percentage od increase?

To calculate the percentage increase:

First: Find out the difference (increase) between the two numbers you are comparing.

It is computed by: Increase = New Number - Original Number

Second: Divide the increase by the original number and multiply the answer by 100.

It is computed by: % increase = Increase : Original Number * 100.

So in the problem:

First step:Increase = 1000 - 100

Increase = 900

Second:

% increase = 900 / 100 x 100%

increase = 900% increase