Main content

## Arithmetic (all content)

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

Lesson 21: Multiplying fractions- Intro to multiplying 2 fractions
- Multiplying 2 fractions: fraction model
- Multiplying 2 fractions: number line
- Multiplying fractions with visuals
- Multiplying 2 fractions: 5/6 x 2/3
- Multiplying fractions
- Finding area with fractional sides 1
- Finding area with fractional sides 2
- Area of rectangles with fraction side lengths
- Multiplying fractions review

© 2023 Khan AcademyTerms of usePrivacy PolicyCookie Notice

# Multiplying fractions review

Review the basics of multiplying fractions, and try some practice problems.

## Multiplying fractions

To multiply fractions, we multiply the numerators and then multiply the denominators.

**Example 1: Fractions**

**Example 2: Mixed numbers**

Before multiplying, we need to write the mixed numbers as improper fractions.

equals, space, start fraction, 8, divided by, 3, end fraction, times, start fraction, 8, divided by, 5, end fraction $\qquad$

We can also write this as 4, start fraction, 4, divided by, 15, end fraction .

*Want to learn more about multiplying fractions? Check out this video.*

### Cross-reducing

Cross-reducing is a way to simplify before we multiply. This can save us from dealing with large numbers in our product.

**Example**

equals, start fraction, start cancel, 3, end cancel, start superscript, 1, end superscript, times, space, 1, divided by, 10, times, start cancel, 6, end cancel, start subscript, 2, end subscript, end fraction

*Prefer a visual understanding of fraction multiplication? Check out one of these videos:*

Multiplying 2 fractions: fraction model

Multiplying 2 fractions: number line

## Practice

*Want to try more problems like this? Check out these exercises:*

Multiply fractions

Multiply mixed numbers

## Want to join the conversation?

- How do you do Cross redusucing?(33 votes)
- Good explanation here : https://www.youtube.com/watch?v=psWT_2QiAVc(4 votes)

- how do you multiply negative

fractions(28 votes)- Multiply the fractions normally, and ensure that the product has the correct sign.

1/2 * 1/2 = 1/4 (Two positives equal a positive.)

-1/2 * -1/2 = 1/4 (Two negatives equal a positive.)

-1/3 * 1/3 = -1/9 (A negative times a positive produces a negative .)

1/3 * -1/3 = -1/9 (The product will be negative, whether the negative number comes first or second.)(22 votes)

- Why do you always have to simplify?(15 votes)
- So the fraction reduced to lowest terms. When we reduce or simplify the fraction, we are writing a fraction in an equivalent form that may be easier to work with.(12 votes)

- What is GCD? thanks to whoever answers it(11 votes)
- greatest common denominator= GCD(1 vote)

- What is the difference between LCD and LCM.(8 votes)
- The mathematical approach to finding the LCM and LCD is the same. For both, we need to find the least common multiple of two or more numbers.
*The least common denominator (LCD) is actually the least common multiple (LCM) of the denominators.*(1 vote)

- How do you multiply the single number with the mixed number?(4 votes)
- You multiply a single number by a mixed number by putting a 1 under the single number.For example 2 + 3 1/2 your new equation would be 2/1 + 3 1/2. This is because 2/1 is the SAME exact thing a 2.(5 votes)

- how do you get the top number on the top like 3 times 2 2/5 how do you get 7 1/5(9 votes)
- In the Multiplying Fractions Review, why is 5/6 x 5/7 clumped together as 5 x 5 with a single line below both and then 6 x 7 also brought together. It seems like an unnecessary step or is there a special meaning to doing this?(5 votes)
- It's just a reminder that when multiplying fractions, we multiply numerator to numerator and denominator to denominator.(13 votes)

- same what's a LCD? can you comment it pls or explan it better.(5 votes)
- If LCD means least common denominator. What does LCM mean?(1 vote)

- I'm realy confused when it comes to math in general.(5 votes)