Question

Caroline needs to find 15% of $128, but she doesn't have a calculator. Thoroughly explain how she can do this mentally, detailing each step. Give the final answer.

Answer 1

The correct answer is $19.2.

Explanation:

Caroline needs to find 15% of $128, but she doesn't have a calculator.

Caroline should start by finding the value of 10 % of any number as it is given by dividing the number by 10. Therefore 10% of $128 is given by
`(128)/(10)` = $12.8.

Now she can find the value of 5% of $128 which is given by dividing the 10% value of any number by 2. Thus 5% of $128 =
`(12.8)/(2)` = $6.4

Thus to calculate the value of 15% of $128 is given by adding 10% of 128 and 5% of 128 = $ (12.8 + 6.4) = $ 19.2.

Thus the value of 15% of $128 is $19.2.