RemeliaMaths Year 4 Fractions, decimals & %
Year 4 fractions of amounts
The objective: Solve problems with harder fractions to calculate and to divide quantities, including non-unit fractions where the answer is a whole number.
The explanation, example and questions are the ones Remelia uses in the app; the questions are not taken from any test paper.
The idea
Finding a non-unit fraction of an amount is two steps: divide by the bottom, multiply by the top.
How to do it
- Divide the amount by the denominator to get one part.
- Multiply by the numerator to get that many parts.
A worked example
2/5 of 45: 45 ÷ 5 = 9, then 9 × 2 = 18.
Watch for
Multiplying first when the numbers do not divide neatly. Divide first: it keeps the numbers small.
Try four questions
-
Ava says: 3/4 of 36 is 9.
Is Ava right? Write the correct answer, not just yes or no.
Show the answer to question 1
Answer: 27 · "No, 27" is right too; "No" on its own scores nothing
Why:
Divide by the denominator, multiply by the numerator.
36 ÷ 4 = 9, then × 3 = 27.
Ava's answer was not right: the correct answer is 27.
-
Dara has 9 pencils and gives away 1/3 of them.
How many are left?
Show the answer to question 2
Answer: 6
Why:
1/3 of 9 = 3. Left: 9 − 3 = 6. (Or: 2/3 of 9 = 6.)
-
To find 2/4 of 60, what do you do?
- A Divide by 4, then multiply by 2
- B Divide by 2, then multiply by 4
- C Multiply by 4, then divide by 2
- D Subtract 2 from 60 and divide by 4
Show the answer to question 3
Answer: A · Divide by 4, then multiply by 2
Why:
Divide by the bottom to get one part (60 ÷ 4 = 15), then multiply by the top (× 2 = 30).
-
Kai says: 3/8 of 56 is 7.
Is Kai right? Write the correct answer, not just yes or no.
Show the answer to question 4
Answer: 21 · "No, 21" is right too; "No" on its own scores nothing
Why:
Divide by the denominator, multiply by the numerator.
56 ÷ 8 = 7, then × 3 = 21.
Kai's answer was not right: the correct answer is 21.
Answers
- 1. 27 · "No, 27" is right too; "No" on its own scores nothing
- 2. 6
- 3. A · Divide by 4, then multiply by 2
- 4. 21 · "No, 21" is right too; "No" on its own scores nothing
The mistakes Remelia names
When a wrong answer to a question like these matches one of these mistakes, the app says what the child seems to have done before they try again.
- Question 1, the answer 9: That is one part. The numerator says how many parts you need, so multiply one part by the numerator.
- Question 1, the answer 48: It looks as if you divided by the numerator and multiplied by the denominator. It is the other way round: divide by the denominator to find one part, then multiply by the numerator.
- Question 2, the answer 3: That is the part given away. The question asks how many are left, so take it away from the whole.