1. Fractions of Quantities
Mathematics
Fractions of Quantities

2. Lesson Objectives The aim of this powerpoint is to help you…
to calculate fractions of quantities
to revise multiplying fractions by fractions

3. Method 1
Write the quantity over 1 and treat as you would when multiplying two fractions together…
Multiply the top numbers together
Multiply the bottom numbers together
Cancel down (if possible) and/or convert your improper fraction back into a mixed number

4. 40 40 Example – Using method 1 120 ÷ 3
Find 2/3 of 60
Remember the line in a fraction means divide, so…
120 3
2 60
3 1 2×
3×1 3 40 × = = = 40
120 ÷ 3  =

5. Method 2 Remember that ‘of’ in maths means multiply so…
Multiply the quantity by the top number of the fraction
Remember the line in a fraction tells you to divide so…
Divide your product by the bottom number of the fraction

6. 40 Example – Using method 2 60 (2 x 60) ÷ 3 = 2 3 ×  Find 2/3 of 60
(120) 2 3 60 40 ×
(2 x 60) 
÷ 3 =

7. Method 3
Find the unitary fraction of the quantity by dividing the quantity by the bottom of the fraction…
Then multiply this by the top number of the fraction.

8. 20 40 Example – Using method 3 60 60 60 ÷ 3 = 2 × 20 = 1 3 of  2 3 of
Find 2/3 of 60 1 3 of 60 20
60 ÷ 3 =  2 3 of 60 40
2 × 20 = 

9. Quick Practice of 40 of 49kg of 40 of 81p of 300cm of £3 A 1 D 2 5 7
B E 4
C F 7
Work out your answers before clicking on to the next slide.
of 40
of 49kg
of 40
of 81p
of 300cm
of £3
HINT: Convert to
pence first!

10. Answers A 1 5 of 40 = B 3 5 of 40 = C 5 6 of 300 = D 2 7 of 49 =
E of 81 =
F of 300p =
40 ÷ 5 = 8
(49 ÷ 7)
then x 2 =
14kg
(40 ÷ 5)
then x 3 =
(81 ÷ 9)
then x 4 = 24
36p
(300 ÷ 6)
then x 5 =
(300 ÷ 10)
then x 7 =
250cm
210p or £2.10

11. What next?
Print out the notes called Frac8. Read them and make sure you answer any questions
Work through pages 1, 2, 3 & 8 of the MyMaths lesson called More Fractions found at:
Work through pages 7 to 10 of the MyMaths lesson called Fractions of Amounts found at:
If you need more practice, try the worksheet called
FracAm-S2.xlsx.
Now move on to the Frac-9 powerpoint