How do you multiply a decimal by a whole number?

Answer 1

This is my way of doing it:

The first step is, you basically multiply like normal vertically. So for example, say you want to multiply 632 x .035 :

632

x .035

---------

3160

+18960

---------

22120

After you have done that, you simply count haw many numbers there are after each decimal point. In this case there is only one decimal point with 3 numbers after it. Let me first say that when you have a whole number, there will ALWAYS be an invisible decimal point at the end of the last number. With that in mind, you now know that there is an invisible decimal point at the end of 22120 which was the partial answer to the multiplication problem above. So now you add the decimal point and the zero to then end of your number(it's ok to have a zero at the end because that indicates nothing, you don't have to, but the point is necessary):

22120.0 When you have this done, you will move the decimal point to the left however many spaces that equals how many numbers you had after the decimal point in total from the original numbers. So, above we said that there was three numbers after the decimal point in the number 0.035, so now you move the decimal point three spaces to the left in your multiplication answer:

22120.0 ------> 22.1200 From here you can get rid of all the zeros after the decimal point, for they are not necessary in this step:

22.12 That's the answer, and that is how you multiply a whole number x a decimal number.

Hope I helped