Example 1
Find of 28.
- The bottom number is 4, so split 28 into 4 equal parts.
- 28 divided by 4 = 7
- One of the four parts is 7.
So: of 28 is 7
Back to National 3
Topic
Fractions
Fractions show equal parts of a whole amount. They are useful for sharing, measuring, recipes, and comparing parts of a group.
Topic explanation
The bottom number of a fraction tells you how many equal parts the whole has been split into. The top number tells you how many of those parts you have.
To find of 32, first divide 32 by 4 to find one quarter. One quarter is 8. Then multiply 8 by 3 to get 24.
Fractions can look different but have the same value. For example, , , and are equivalent because they each show half of the whole.
Quick methods
- Find a fraction of an amount
- Divide by the bottom number, then multiply by the top number.
- Simplify
- Divide the top and bottom by the same number.
- Equivalent fractions
- Multiply or divide the top and bottom by the same number.
- Same denominator
- If the bottom numbers match, work with the top numbers.
Worked examples
Example 2
Find of 40.
- Divide by the bottom number first: 40 divided by 5 = 8
- That means of 40 is 8.
- Multiply by the top number: 8 × 3 = 24
So: of 40 is 24
Example 3
A recipe uses of a 200 g bag of flour. How much flour is used?
- Find first: 200 divided by 4 = 50 g.
- The recipe needs 3 quarters.
- 50 g × 3 = 150 g
So: The recipe uses 150 g of flour.