Fractions of Sets and Amounts
Fractions can describe part of a set or amount. To find a fraction of a number, divide by the denominator and then multiply by the numerator.
What You Need to Know
Key Concept Diagram
To find 1/4 of 20, divide 20 by 4 to get 5
To find 3/4 of 20, first find 1/4 (=5) then multiply by 3 (=15)
Fractions can be used with money, lengths, and other measurements
If 3/5 of a number is 15, then 1/5 is 5, and the whole is 25
Key Vocabulary
Fraction of a set
Using a fraction to describe part of a group of objects
Denominator
The bottom number, showing how many equal parts to divide into
Numerator
The top number, showing how many parts we take
Unit fraction
A fraction with 1 as the numerator, like 1/3 or 1/5
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
What is 1/4 of 36?
Question 2
What is 3/5 of 25?
Question 3
If 2/3 of a bag of marbles is 18, how many marbles are in the whole bag?
Key Concepts Summary
- ●To find 1/4 of 20, divide 20 by 4 to get 5
- ●To find 3/4 of 20, first find 1/4 (=5) then multiply by 3 (=15)
- ●Fractions can be used with money, lengths, and other measurements
- ●If 3/5 of a number is 15, then 1/5 is 5, and the whole is 25