How do you do simple interest in math

simple interest:

principal x (1 + (rate as decimal x number of years))

example if you put 100 dollars in a bank for 5 years at 5% interest at the end of the 5 years you would have:

100 x (1 + (0.05 x 5)) = 100 x (1 + (0.25)) = 100 x 1.25 = 125 dollars

125-100 = 25 dollars interest