Grade 3, Operations
Find the missing number: add and subtract
Find the unknown start, change or result in equations to 100.
Three levels
One skill, rising difficulty
Each sheet carries one level. The three are the same skill at rising difficulty, each named for what it practises.
- Level 1: Result unknown
- Write the number that goes in the box.
- Level 2: Change unknown
- Write the number that goes in the box.
- Level 3: Start unknown
- Write the number that goes in the box.
Worked example
How the sheet explains it
The helper printed at the top of each sheet: one solved example and the steps a student follows, before the first question. Every number sentence in it is proven by the same checker as the answer key.
Level 1: Result unknown
47 + 25 = 72
- The box is the answer. Add or subtract, as the sign says.
- Add the tens: 47 + 20 = 67.
- Add the ones: 67 + 5 = 72, so 47 + 25 = 72.
- To subtract, take away the tens, then the ones.
Level 2: Change unknown
38 + 14 = 52
- The box is the number added to 38 to make 52.
- Count up: 38 + 2 = 40, then 40 + 12 = 52.
- The jumps are 2 + 12 = 14, so 38 + 14 = 52.
- If the box is taken away, as in 52 − box = 38, count up from 38 the same way.
Level 3: Start unknown
37 + 26 = 63
- The box is the number you start with. To undo adding, take away.
- 63 − 26: take away 20, then 6. 63 − 20 = 43 and 43 − 6 = 37.
- Check: 37 + 26 = 63.
- To undo taking away, add: if 18 was taken away and 25 is left, 25 + 18 = 43.
Goes with
Reference sheets
One-page helpers a student keeps beside this sheet:
- Solving equations
Every reference, facts and support sheet is listed in the worksheet catalogue.
In the BC curriculum
Content standards
The British Columbia content standard this skill is written for, by the codes used across this site:
- bc.math.3.c.8
The wording of each standard is on the Province's mathematics curriculum page.
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