This is such a fun math tool! This is a simple way to add fractions without having to rewrite equivalent fractions with the same denominator.
Transcript
0:00
Hey, Tutoring Bee fans! I am back with another video. I’m so sorry it’s taken me so long to get another one out to you.
0:07
This video is about adding and subtracting fractions using the butterfly method. Normally, when we add or subtract fractions, we have to find common denominators, create equivalent fractions, and then add. But this method is much easier!
0:19
I have a couple of fractions set up that I’m going to add together using the butterfly method. It’s called that because of the shape we create when we solve it.
0:26
Let’s start! First, we multiply diagonally. I’m going to multiply 3 × 1, which equals 3, and write that at the top.
0:40
Next, I multiply the other diagonal: 2 × 4, which equals 8. I’ll write that up top as well.
0:49
Now for the denominator, which is the “body” of the butterfly. I multiply the two denominators: 3 × 4 = 12.
0:57
To find our answer, I add the two numbers at the top: 8 + 3 = 11. So, our final fraction is 11/12. Pretty cool, right?
1:07
I know you might be wondering, Why does this work? I’m so glad you asked! Let me show you using fraction pieces.
1:16
Here, I have my fraction pieces for reference. This is one whole. Now, I have my fractions: 2/3 + 1/4.
1:27
Whenever we multiply fractions, we’re essentially asking how many equal pieces we can split them into.
1:36
When I multiply 2 × 4, I’m figuring out how to divide each third into four equal pieces. Since 1/3 divided into four pieces equals 4/12, and I have two-thirds, that means I have 8/12 in total.
1:52
Now let’s look at 1/4. I multiply 1 × 3, meaning I’m splitting the fourths into three equal pieces. That gives me 3/12, which is equivalent to 1/4.
2:23
When I add 8/12 + 3/12, I get 11/12—just like we calculated using the butterfly method!
2:30
This method also works for subtraction. Let me show you an example.
2:34
For this subtraction problem, we’ll follow the same steps. I start by multiplying diagonally:
2:40
2 × 2 = 4, and 1 × 5 = 5.
2:50
Next, I multiply the denominators: 2 × 5 = 10.
2:57
Since this is subtraction, I subtract the two numbers at the top: 5 – 4 = 1.
3:03
That gives me the final fraction 1/10.
3:07
Pretty simple, right? The butterfly method is a quick and easy way to add and subtract fractions with different denominators.
3:13
I hope you liked this video! Please subscribe to my channel and let me know what you think. Thanks!
Extra Credit
Here are some other resources you might find helpful!
- 4th-grade Math Review – https://bit.ly/2ZYYl3A
- 5th-grade Math Review – https://bit.ly/32SOeiJ
- What’s My Operation? Game – https://bit.ly/37MxKve
- Order of Operation Activity – http://bit.ly/GoogleBoom
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