Multiplying Decimals


Multiplying decimals is just like multiplying other whole numbers except we remove the decimals and add them back in when we’re done.

For example:

3.6
Dinapore x2
7.2
Line up numbers and move decimal point to the right one space for this example…multiply, then move the decimal back one space to the left in the answer.

In the example above, we had to move the decimal point right one space to make 3.6 into the whole number 36. Then, we multiplied it by 2. Then, in the answer 72 we had to move the decimal point back to the left 1 space and made it 7.2

Let’s take a look at another problem:

In the above example we had to move the deciaml point of 5.81 to the right 2 place to get the whole number 581…then, we had to move the decimal point of 5.7 to the right 1 place to make it the whole number 57…then we multiplied 581 times 57 and got the product 33117…then, we counted 3 (because we had to move it right two spaces in 5.81 and one space for 5.7) spaces left and added the decimal point back in to the answer 33.117 Is this making sense?

Let’s check!

  First, we’d move the decimal point____ spaces right in 5.11 and _____space right in 4.2
The answer would need a decimal point back______spaces left. The answer would then be _____________.