A certain amount earns 10percent interest compounded annually .What is the minimum number of years(in integers) it takes to double the amount ??
8 years increases the original amount by a factor of 1.1^8 = 2.1436
7 years increases the original amount by a factor of 1.1^7 = 1.9487
Since you want an integer answer, you need 8 years to double your money.