Primary 1 Mathematics Addition Subtraction Quiz

Primary 1 Mathematics Quiz - Addition Subtraction (Answer Key)

Total Marks: 30

Section A: Multiple Choice Questions (5 × 1 mark = 5 marks)

1. Answer: (3) 8
Explanation: Count the apples in both groups. Group A has 5 red apples. Group B has 3 green apples. To find the total, add: 5 + 3 = 8.
Method: Count all objects in both groups.
Common mistake: Counting only one group or miscounting the total.

2. Answer: (2) 4 + 6 = 10
Explanation: The question asks for a number sentence showing 6 + 4. Addition is commutative, so 6 + 4 = 4 + 6 = 10. Option (2) shows 4 + 6 = 10, which is equivalent. Option (4) is incorrect because 6 + 4 = 10, not 11.
Key concept: Commutative property of addition (order does not change the sum).

3. Answer: (2) 5
Explanation: Start with 9 balloons. 4 burst (are taken away). Subtract: 9 − 4 = 5 balloons left.
Method: Subtraction as "taking away".
Common mistake: Adding instead of subtracting (9 + 4 = 13, option 1).

4. Answer: (2) 4
Explanation: In a number bond, the whole (10) is split into two parts. One part is 6. The other part is 10 − 6 = 4. Check: 6 + 4 = 10.
Method: Part = Whole − Known Part.
Key concept: Number bonds show part-part-whole relationships.

5. Answer: (3) 8
Explanation: 15 − 7 = 8. Count back 7 from 15: 14, 13, 12, 11, 10, 9, 8. Or use number bond: 15 = 7 + 8.
Method: Counting back or using known number bonds to 10/20.

Section B: Short Answer Questions (10 × 2 marks = 20 marks)

6. (a) 8 + 5 = 13
(b) 12 − 4 = 8
Explanation:
(a) Count on 5 from 8: 9, 10, 11, 12, 13. Or make 10: 8 + 2 = 10, then +3 = 13.
(b) Count back 4 from 12: 11, 10, 9, 8. Or 12 = 4 + 8.
Marks: 1 mark each correct answer.

7. 10 + 6 = 16
Explanation: The first ten frame is full (10 counters). The second ten frame has 6 counters. Total = 10 + 6 = 16.
Method: Use ten frames to visualise tens and ones.
Marks: 1 mark for correct numbers in blanks, 1 mark for correct total.

8. 11, 9
Explanation: The pattern decreases by 1 each time: 14, 13, 12, 11, 10, 9.
Method: Identify the rule (subtract 1) and continue.
Marks: 1 mark each correct number.

9. 6 stickers
Working: 11 − 5 = 6
Explanation: Mary starts with 11 stickers. She gives away 5. Subtract to find how many left: 11 − 5 = 6.
Key phrase: "gives away" or "left" signals subtraction.
Marks: 1 mark for working (11 − 5), 1 mark for correct answer with unit.

10. 15 children
Working: 7 + 8 = 15
Explanation: 7 boys and 8 girls. "Altogether" means add the two groups: 7 + 8 = 15.
Method: Make 10: 7 + 3 = 10, then +5 = 15. Or count on from 8.
Marks: 1 mark for working (7 + 8), 1 mark for correct answer with unit.

11. (a) 7
(b) 14
Explanation:
(a) 9 + ? = 16 → ? = 16 − 9 = 7. Check: 9 + 7 = 16.
(b) ? − 6 = 8 → ? = 8 + 6 = 14. Check: 14 − 6 = 8.
Method: Use inverse operations (subtraction for missing addend, addition for missing minuend).
Marks: 1 mark each.

12. 7
Working: 12 − 5 = 7
Explanation: Cross out 5 flowers from 12. Count remaining: 7. Equation: 12 − 5 = 7.
Visual method: Crossing out models subtraction as taking away.
Marks: 1 mark for crossing out 5 flowers (implied), 1 mark for correct answer.

13. 9 + 6 = 15
6 + 9 = 15
15 − 9 = 6
15 − 6 = 9
Explanation: From the number bond (whole = 15, parts = 9 and 6), we can write 2 addition and 2 subtraction equations (fact family).
Key concept: Fact families — related addition and subtraction equations using the same three numbers.
Marks: ½ mark each correct equation (4 equations × ½ = 2 marks). Accept equations in any order.

14. 7 marbles
Working: 18 − 11 = 7
Explanation: Tom started with 18 marbles. After losing some, he has 11. To find how many lost: subtract the remaining from the original: 18 − 11 = 7.
Method: Missing subtrahend: Original − Remaining = Lost.
Marks: 1 mark for working (18 − 11), 1 mark for correct answer with unit.

15. (a) 12
(b) 8
Explanation:
(a) 20 = ? + 8 → ? = 20 − 8 = 12. Check: 12 + 8 = 20.
(b) 17 − ? = 9 → ? = 17 − 9 = 8. Check: 17 − 8 = 9.
Method: Inverse operations.
Marks: 1 mark each.

16. 4 + 5 + 3 = 12
Explanation: Count the stars in each group: Group 1 has 4 stars, Group 2 has 5 stars, Group 3 has 3 stars. Add all three groups: 4 + 5 + 3 = 12.
Method: Add three numbers by grouping: (4 + 5) + 3 = 9 + 3 = 12, or 4 + (5 + 3) = 4 + 8 = 12.
Marks: 1 mark for correct numbers in blanks, 1 mark for correct total.

17. 18
Working: 13 + 5 = 18
Explanation: Start at 13 on the number line. Jump forward 5 steps: 14, 15, 16, 17, 18. Land on 18.
Method: Counting on using a number line.
Marks: 1 mark for working (using number line or 13 + 5), 1 mark for correct answer.

18. 6 and 4 (or 3 and 7, or 8 and 2)
Explanation: Pairs that make 10: 6 + 4 = 10, 3 + 7 = 10, 8 + 2 = 10. Circle any one correct pair.
Key concept: Number bonds to 10.
Marks: 1 mark for identifying a correct pair, 1 mark for writing the pair correctly.

19. 7 cupcakes
Working: 16 − 9 = 7
Explanation: Start with 16 cupcakes. 9 are eaten (taken away). Subtract: 16 − 9 = 7 cupcakes left.
Method: Count back 9 from 16, or use number bond: 16 = 9 + 7.
Marks: 1 mark for working (16 − 9), 1 mark for correct answer with unit.

20. Example story: "There are 14 pencils in a box. 6 pencils are taken out. How many pencils are left in the box?"
Explanation: A subtraction story for 14 − 6 = 8 must have a starting amount of 14, an action of taking away 6, and a question asking for the remaining amount (8). Accept any reasonable context (pencils, apples, children, etc.) that matches the equation.
Marks: 1 mark for correct starting amount (14), 1 mark for correct action (take away 6), 1 mark for correct question/ending (8 left).

Section C: Word Problems (2 × 2 marks + 1 × 3 marks = 7 marks)

16. There are 11 birds on the tree now.
Working:
14 − 6 = 8 (birds left after 6 fly away)
8 + 3 = 11 (3 more birds come)
Or: 14 − 6 + 3 = 11
Explanation: Two-step problem. First subtract the birds that flew away (14 − 6 = 8). Then add the birds that came (8 + 3 = 11).
Marks: 1 mark for first step (14 − 6 = 8), 1 mark for second step (8 + 3 = 11) and correct final answer in a sentence.

17. There are 7 yellow crayons.
Working:
5 + 4 = 9 (red and blue crayons)
16 − 9 = 7 (yellow crayons)
Explanation: First find total red and blue crayons: 5 + 4 = 9. Then subtract from total crayons to find yellow: 16 − 9 = 7.
Alternative: 16 − 5 = 11, then 11 − 4 = 7.
Marks: 1 mark for finding red + blue (5 + 4 = 9), 1 mark for subtracting from total (16 − 9 = 7) and correct final answer in a sentence.

18. Mrs Tan had 8 cookies left.
Working:
7 + 5 = 12 (cookies given away)
20 − 12 = 8 (cookies left)
Or: 20 − 7 = 13, then 13 − 5 = 8
Explanation: Two-step problem. First find total cookies given away: 7 + 5 = 12. Then subtract from original: 20 − 12 = 8.
Marks: 1 mark for total given away (7 + 5 = 12), 1 mark for subtracting from total (20 − 12 = 8), 1 mark for correct final answer in a complete sentence.

Total: 30 marks

Marking Notes:

• Accept correct working even if final answer is missing unit, but deduct ½ mark for missing unit in word problems (Section C).
• For fact family (Q13), accept any order of the four equations.
• For multi-step word problems, award method marks for correct intermediate steps even if final answer has a calculation error.
• Encourage students to show working using number bonds, counting on/back, or making ten strategies.
• For Q18 (subtraction story), accept any context that correctly represents 14 − 6 = 8.
• For Q18 (circle numbers making 10), accept any valid pair: (6,4), (3,7), or (8,2).