(I have attached an example for reference)
1) Product means multiply, so we will multiply the decimal numbers.
2) First multiply both the numbers just the way you multiply two whole numbers.
3) note that WHILE multiplying you DON'T put the decimal point. Put the decimal point once you get your FINAL answer.
4) Once multiplied, count the total number of places after the decimal in both the numbers which were given. i.e, in the example it's 2 decimal places, one decimal place in 24.5 and one in 3.2, which means the total decimal places here are two.
5) now in your answer, start counting the decimal places from the right side of the number. For example in 7840, we start counting two decimal places from the right side of it and stop at 4 and put a decimal point there. This way we get 78•40.
Hope that helps...