Multiplying and dividing fractions · Usually met around P5
Fractions as division
a ÷ b = a/b.
How to do it
Method
a ÷ b = a/b
3 ÷ 4 = 34; 15 is 34 of 20
Another way
Draw the sharing
Cut each in 4, 3 pieces each → 34
In full
Share 3 pizzas equally among 4 people and each gets 3 ÷ 4 = 34 of a pizza: dividing one whole number by another gives a fraction, the number divided on top and the divisor below. Way 1: write a ÷ b = a/b straight away and simplify. Way 2: draw it: cut each pizza into 4, and each person takes 1 piece of every pizza, 3 pieces, which is 34. “What fraction of B is A” means A ÷ B: 15 is 1520 = 34 of 20. Make the units the same first: 45 minutes is 4560 = 34 of an hour.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
What fraction of 56 is 7?
Answer in simplest form
Show the answer and working
Answer: 18
7 ÷ 56 = 756, which simplifies to 18.
Example 2
12 ÷ 9 = □ (as a fraction in its simplest form; an improper fraction is fine)
Answer in simplest form
Show the answer and working
Answer: 43
The number divided goes on top, the divisor below: 129, simplified 43.
Example 3
2 pizzas are shared equally among 9 people. How much pizza does each get?
- A. 92 of a pizza
- B. 211 of a pizza
- C. 29 of a pizza
- D. 19 of a pizza
Choose the right answer
Show the answer and working
Answer: C. 29 of a pizza
2 ÷ 9 = 29: 29 each.
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