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## Arithmetic (all content)

### Course: Arithmetic (all content)>Unit 5

Lesson 10: Decomposing fractions

# Decomposing a mixed number

Sal uses fraction models to decompose 2 1/4. Created by Sal Khan.

## Want to join the conversation?

• 1/1 = 8/8 because 1/1 is 1 out of 1 which is 1, and 8 out of 8 which is 8. the fraction sign is also the division symbol, so 1 divided by 1 =1, and 8 divided by 8= 1.
• i cant do a mixed number
• Why?
• They help you with cooking. You will need fractions if you are trying to figure out how much sugar you need for a cake. (‾◡◝)
• i can't do anything with fraction is just too hard.
• So start with a 20x20 times table and learning equivalent fractions. Pick any two numbers (like 2 and 5) and start going down both lines 2/5 = 4/10 = 6/15 = 8/20 ... This is where I like to start talking about fractions. So if you have 25/65, you can see that they are both on the 5 line, so going backwards, you get 5/13. This helps to find and reduce fractions.
Next, learn to multiply fractions (3/2)(5/4) multiply top and bottom 15/8. Since there is no line (except the one line) that has both 15 and 8, it cannot be reduced. Move to multiplications that can reduce, (4/5)(10/2) so when you multiply, you get 40/10. Since both 40 and 10 are on the 10 line, you can go up to 4/1, and you do not need to divide by 1, so you get 4.
Once you get good at these, then you can start to learn to add and subtract fractions, divide fractions, and then start working with mixed numbers.
• i hate fortnite
• Can a fraction be cubed?
• Sure can! Take 4/5 for example. 4 cubed is 64, and 5 cubed is 125. So 4/5 cubed is 64/125.
• We should find the l.c.m while addition and subtraction or we can use the same method for multiplication and division?
• When multiplying or dividing (which is basically multiplying the first fraction by the reciprocal of the second fraction, "flipped") fractions, you don't have to find the LCM for the denominator because you're multiplying the denominators. It's a good idea to simplify the fractions before, though, so the numbers you get at the end aren't too large.