Explain how estimation you place the decimal point when multiplying 3.9 & 5.3

3.9 and 5.3, when rounded off and mult. together, produce the product 20.
Thus, the decimal point must follow the first two digits of your answer, whether estimate or "exact."

3.9*5.3 = 20.67 by calculator.

Do you have answer choices?

There is 240 red cars and there is 400 blue cars because 240/3=80 and 80*5=400