How to Multiply and Divide Fractions
Multiplying and Dividing Fractions
To multiply two fractions simply multiply the numerators and multiply the denominators. 3 times 2 is 6, and 4 times 5 is 20. Then we can simplify, 6 and 20 are both divisible by 2.
Divide your numerator by 2 and the denominator by 2. 6 divided by 2 is 3, and 20 divided by 2 is 10. 3/4 times 2/5 is 3/10. Now there is somewhat of a trick or a shortcut when multiplying fractions, so I’ll show you that. 3/4 times 2/5.
When you’re multiplying fractions before you multiply, look and see if you can cross cancel. When you’re cross cancelling, you’re looking at a numerator and a denominator. 3 and 5, if we look at 3 and 5, there’s nothing we could divide both of those by.
However, you could divide 2 and 4 both by 2. 4 divided by 2 is 2, and 2 divided by 2 is 1. Then you multiply like normal, 3 times 1 is 3, and 2 times 5 is 10. Cross cancelling saves you the step of simplifying, but you get the same result.
Make sure that you don’t ever try and cross cancel numerators with each other. It’s only those diagonal numbers that you can cross cancel. You cross cancel a numerator with a denominator. Now let’s look at division. We’re going to divide 2/3 by 3/4.
You know what’s funny about dividing fractions, is that you don’t. We don’t divide fractions. Instead we copy the first fraction, we change division into multiplication, and we flip our last fraction. We copy the first 2/3, we change division into multiplication, and we flip the last fraction over.
It’s now 4/3. Now we multiply like normal. 2 times 4 is 8, and 3 times 3 is 9. That can’t be simplified so 8/9 is our answer. When dividing fractions just remember C-C-F, copy the first fraction exactly as it is, change division to multiplication, and flip the last fraction.