How do you multiply decimals by whole numbers

Step-by-step explanation: To multiply a decimal by a whole number, first line up the numbers and begin multiplying as if we were multiplying two whole numbers.  

Let's look at an example.

2.9 x 6 = ?

Steps for multiplying

6 x 9 is 54 so we bring down the 4 and carry the 5.

6 x 2 is 12 and if we add 5 to that, we get a sum of 17.

Now we have 174.

Now here is the trick with multiplication problems involving decimals. As our last step, we must determine where the decimal goes in our answer by counting the total number of digits to the right of the decimal point in our original numbers,

Since 2.9 has one digit to the right of the decimal point and 6 has no digits to the right of the decimal point, we have a total of one digit to the right of the decimal point in our original numbers.

This means that we will have one digit to the right of the decimal point in our answer. So our answer is 17.4.