To find the product of \(1.39\) and \(100\), Justin can use the fact that multiplying by \(100\) is the same as moving the decimal point two places to the right. This is because \(100\) can be expressed as \(10^2\).
Therefore, the correct response is:
He knows that 100 is 10 to the power of 2, so he needs to move the decimal point in 1.39 two places to the right.