Charlie is evaluating the product of 0.09 and 0.05. He multiplies, and before placing the decimal, arrives at an answer of 45. After considering the decimal placement, what is Charlie’s final answer?

Multiply 9 × 5 to get 45. The factors 0.09 and 0.05 have a total of four digits after their decimal points, so place the decimal four places from the right in 45. Charlie’s final answer is 0.0045.

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