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.
So, divide your numerator by 2, and the denominator by 2. 6 divided by 2 is 3, and 20 divided by 2 is 10. So, 3/4 times 2/5 is 3/10.
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The transcript is for your convenience
Then, we can simplify. 6 and 20 are both divisible by 2. So, divide your numerator by 2, and the denominator by 2. 6 divided by 2 is 3, and 20 divided by 2 is 10. So, 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-canceling, you’re looking at a numerator and a denominator.
So, 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. So, 4 divided 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.
So, cross canceling saves you this 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 members that you can cross cancel, to cross cancel a numerator with a denominator.
Now, let’s look at division. We’re going to divide 2/3 by 3/4.
And 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. So, we copy the first, 2/3, we change division into multiplication, and we flip the last fraction over, so it’s now 4/3.
And now, we multiply like normal. 2 times 4 is 8, and 3 times 3 is 9. And that can’t be simplified, so 8/9 is our answer.
When dividing fractions, just remember CCF. Copy the first fraction exactly as it is, change division to multiplication, and flip the last fraction.
This lessons is a part of Fraction chapter of GED Math Prep and is included in every GED Practice Test and the real GED exam. Click here to take a GED Practice Test now.