Grade 5 · Maths · Lessons
Say it, do not work it out
🗣️say✍️write🔵brackets🧮copies
Say it, don't work it out.The big ideaBrackets hold the part done first. A number times a sum is that many copies of the sum.
How it works
Brackets hold the part done first. A number times a sum is that many copies of the sum.
'Subtract 10 from 12, then multiply by 9' is 9 × (12 − 10).
You can describe an expression without working it out.
Example 1: Write it
- Write in numbers: subtract 10 from 12, then multiply by 9
- Subtract 10 from 12 goes inside brackets.
- Then multiply by 9.
- So the answer is 9 × (12 − 10).
Example 2: Read it
- Which sentence is true of 4 × (22265 + 949)
- Look at the brackets: 22265 + 949 is one amount.
- 4 times it means 4 copies of that sum.
- So the answer is 4 times as large as 22265 + 949.
Example 3: Another write
- Write in numbers: add 31 and 22, then multiply by 14
- Add 31 and 22 goes inside brackets.
- Then multiply by 14.
- So the answer is 14 × (31 + 22).
Words to know
- expression
- Numbers and signs that make a calculation.
- sum
- The answer to an addition.
Watch out
- Put the part done first in brackets.
- You don't need to work it out.
- Read 4 × (a + b) as 4 copies of the sum.
Try it
- Write: add 5 and 3, then multiply by 2.
- Write: subtract 4 from 9, then times 3.
- What does 5 × (2 + 1) mean in words?
- Do you need to work out the answer?
Answers: 1. 2 × (5 + 3) · 2. 3 × (9 − 4) · 3. 5 times the sum of 2 and 1 · 4. no
For grown-upsSay a calculation in words and ask your child to write it with brackets.