A fraction of a set

Primary 6 Fractions study guide: the whole chapter, step by step

About this subtopic

The bottom number makes the equal groups. The top number says how many groups to take. In the lesson. The top number says how many groups to take.

Lesson video, with the working

Finding a fraction of a set

2 min 23 s

The film teaches 2 questions in turn. Each question shows first; its working is written as the film explains it.

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Today's question

A box holds 30 eggs. 2/5 of the eggs are brown. How many of the eggs are brown?

  1. 12 eggs are brown.

Ans: 12

Example 1

The same box holds 30 eggs. 3/5 of the eggs are white. How many of the eggs are white?

  1. 18 eggs are white.

Ans: 18

How to solve it
  1. Look at the bottom number of the fraction. Two fifths has 5 at the bottom, so split the 30 eggs into 5 equal groups.
  2. Count one group: 30 split into 5 equal groups is 6 eggs in each.
  3. Look at the top number. It is 2, so take 2 of the 5 groups.
  4. Count what you took: 2 groups of 6 is 12 eggs.
  5. Or write two fifths times 30: cross out the 5 and 30 to get 1 and 6, and 2 times 6 is 12.

The bottom number makes the equal groups. The top number says how many groups to take.

Practice questions with worked solutions

Question 1 is free to try. The other question opens in the free trial, each with its full working.

Intermediate

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Question 1 of 2 · Intermediate · free to tryThere are 84 chairs in a hall. 5/7 are blue and the rest are white. How many…There are 84 chairs in a hall…

There are 84 chairs in a hall. 5/7 are blue and the rest are white. How many more blue chairs than white chairs are there?

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Video solution · 1 min 30 s

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Working

  1. blue chairs = 5 units; white chairs = 7 − 5 = 2 units
  2. difference = 5 − 2 = 3 units
  3. 1 unit = 84 ÷ 7 = 12
  4. 3 units = 3 × 12 = 36

Answer: 36

For parents

How do you solve fraction of a set questions in P6?

Finding a fraction of a set is the starting point for most fraction word problems in Primary 6.

What your child learns here

Finding a fraction of a set is the starting point for most fraction word problems in Primary 6. It revises multiplying a fraction by a whole number from the year before, and shows the picture behind the multiplication, so that your child knows what the numbers in the calculation stand for.

  • Split a set into equal groups using the bottom number of the fraction.
  • Take the number of groups given by the top number.
  • Write the same step as a fraction times a whole number, cancelling common factors first.
  • Use a fraction of a set to find the other part, or the difference between two parts.
Does the answer make sense?

A fraction of a set must be a whole number of items smaller than the set, since the set splits into equal groups, like 18 buns into thirds. If your child takes a fraction above one half, such as five sevenths of the chairs, it must be more than the part left over.

How to practise these questions

The Intermediate questions train finding a fraction of a set for two different parts and then comparing those parts. If a fraction of a set is confusing, read the written step-by-step solution with your child.

Questions parents ask

Is fraction of a set taught in Primary 6? It is taught in earlier years and revised here, because multiplying a fraction by a whole number is the step behind many Primary 6 fraction word problems.

Should my child cancel before multiplying? It helps. Cancelling a common factor between the bottom number and the whole number first keeps the numbers small, so there is less to multiply and less to simplify at the end.

Does my child need to draw the groups every time? No. Drawing them shows what the bottom and top numbers mean, and once that is clear, the written step of a fraction times a whole number is enough.