Multiplying and Dividing Decimals

By: Libby Dooley

Multiplying Decimals

In the real world, people are multiplying decimals all the time without noticing and I'm going to show you where they do it at. When you pay for gasoline your multiplying decimals. You see how much it is a gallon and how much gallons you will need. Or when you go to the store and you get more then one of the same thing. You multiply how much money that thing is, times how much of that thing you got. Another example is if you go out to eat and your family ordered two or more of the same thing. The waiter or waitress can multiply how expensive that item is, and how many your getting to get a total for your family much faster.

Dividing Decimals

You also divide decimals without noticing, and here are some examples. When you family goes out to eat and your parents decide to split the bill. They have to divide the total in half. Or if you go to the store and want to buy one apple but you don't know the price. All you see is the price it is per pound. The sign also says how many apples were in a pound. So you divide the total per pound into how many apples there are in a pound. Also another example is gasoline. The gas station gives you the total of how much the gas will cost but you want to know how much it is per gallon. You will have to divide how much gallons you got from the total of the gasoline.

How to multiply and divide decimals

Someday you might run into situations where you need to multiply and divide decimals, and if you don't know how I'm going to tell you. To multiply decimals line up the numbers like a normal multiplication problem but leave the decimal there. Then solve like a normal multiplication problem. Once your done solving it's time to put the decimal back in place. To do that count how many numbers are behind the decimal at the very top. Then move the decimal to the right that many times. Then you will have your answer and that's how you solve a multiplication problem. Now it's time to solve a division problem with decimals when there's a decimal in the dividend. If there's a decimal in the dividend it's okay, still solve the division problem like normal and when you get your answer bring the decimal wherever it is in the dividend straight up. Nothing changes when your solving the division problem except for bringing the decimal straight up. Now I'm going to tell you how to solve a division problem when there's a decimal in both the dividend and divisor. First, you have to move the decimal to the right as many times as it takes in the divisor until the decimal is turned into a whole number, but because you moved the divisors decimal you have to move the dividend decimal. To do this you move the decimal as many times as you moved the decimal in the divisor. Now it's time to solve. Again solve like normal and when you get your answer bring the decimal up from wherever it is in the dividend. Now you have just solved the division problem. Hopefully now you know how to multiply and divide decimals.