Question

1.0 X 21 = 21 or 210 because of the decimal point, I just don't remenber how the decimal point works.

Answer 1

Here's one way of looking at it.

If you buy something for $1.25, you know you are going to pay a one dollar bill and a 25-cent piece (a quarter). The decimal comes after the whole number.

So 1.0 is the same as 1.

1 * 21 = 21