Multiplying fractions

A fraction is a part of a whole. In the last lesson, you learned how to add and subtract fractions. But that’s not the only kind of math you can do with fractions. There are times when it will be useful to multiply fractions too.

You are watching: 4/5 times 4/5

Click through the slideshow to learn how to write a multiplication problem with fractions.

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Let's set up a multiplication example with fractions. Suppose you drink 2/4 of a pot of coffee every morning.

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But your doctor just told you that you need to cut down your coffee drinking by half.

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Now you need to figure out how much 1/2 of 2/4 of a pot of coffee is.

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This may not look like a multiplication problem. But when you see the word of with fractions, it means you need to multiply.

To set up the example, we'll just replace the word of with a multiplication sign.

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Now our example is ready to be solved.

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Unlike regular multiplication, which gives you a larger number...

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Unlike regular multiplication, which gives you a larger number...multiplying fractions will usually give you a smaller number.

So when we multiply 1/2 times 2/4...

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So when we multiply 1/2 times 2/4...our answer will be smaller than 2/4.

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Here's another example. Let's say you have 3/5 of a cup of chocolate filling.

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You want to put an equal amount of filling in each of these 4 cupcakes.

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You could say that you want to put 1/4 of 3/5 of a cup of filling in each cupcake.

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Just like we did before, we'll change the word of into a multiplication sign.

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And now our fractions are ready to be multiplied.

Try This!

Try setting up the multiplication problem below. Don't worry about solving it yet!

A recipe calls for 2/3 of a cup of milk. You want to cut the recipe in half.


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Note: Although our example says the correct answer is 2/3 x 1/2, remember, with multiplying order does not matter. 1/2 x 2/3 would also be correct.

Solving multiplication problems with fractions

Now that we know how to set up multiplication problems with fractions, let's practice solving a few. If you feel comfortable multiplying whole numbers, you're ready to multiply fractions.

Click through slideshow to learn how to multiply two fractions.

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Let's multiply to find 1/2 of 7/10.

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Just like we did earlier, we'll replace the word of with a multiplication sign. Now we're ready to multiply.

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First, we'll multiply the numerators: 1 and 7.

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1 times 7 equals 7, so we'll write 7 to the right of the numerators.

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When we added fractions, the denominators stayed the same. But when we multiply, the denominators get multiplied too.