Grade 4 · Math · Unit 8 of 12
Equations
Find the mystery number
What your child practises
Solving one-step equations with a box or letter for the unknown, using all four operations, and matching equations to word problems.
Nunavut Curriculum approved guide: Alberta Mathematics K–9 (2007), Patterns and Relations · equations with a symbol for an unknown number
How we explain it
Children can open this short lesson before they practise.
- An equation says two things are equal.
- Use the opposite operation to find the missing number.
- Check by putting your answer back in.
Example: ☐ + 7 = 15. What is ☐? Opposite of adding 7 is subtracting 7. 15 − 7 = 8. Answer: 8
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Which equation matches the story?
Sam had 787 stickers.
Sam gave some away.
Now Sam has 496 stickers.
- 787 − ☐ = 496
- 787 + ☐ = 496
- 787 + 496 = ☐
- ☐ − 787 = 496
787 − ☐ = 496
Hint: Sam started with 787. The box is the number given away. Taking it away left 496.
Question 2
What number goes in the box?
744 − = 493
- 261
- 1237
- 250
- 251
251
Hint: Taking away the box number leaves 493. So the box number is 744 − 493 = 251.
Question 3
What number goes in the box?
÷ 2 = 9
- 11
- 18
- 20
- 16
18
Hint: Work backwards with multiplication: if a number shared into 2 groups gives 9, the number is 9 × 2 = 18.
Question 4
What number goes in the box?
2 × = 10
answer box
5
Hint: What times 2 makes 10? Divide to find it: 10 ÷ 2.
Question 5
What number goes in the box?
12 ÷ = 2
- 6
- 2
- 5
- 7
6
Hint: 12 split into groups gives 2. Think: 2 × what number = 12? 2 × 6 = 12.
Question 6
What number goes in the box?
383 + = 415
answer box
32
Hint: What do you add to 383 to make 415? Subtract to find it: 415 − 383.