Primary 1 Mathematics Numbers Quiz

Primary 1 Mathematics Quiz - Numbers — Answer Key

Total Marks: 30 Topic: Numbers (Whole Numbers up to 100)

Marking Notes:

• Accept clear numerals in answers.
• For word problems, full working must be shown to receive the method mark.
• Common mistakes: students reversing the order when arranging numbers, or subtracting the wrong way around.

Section A: Counting and Place Value

1. [1 mark] Answer: 8 Explanation: Count each star one by one. There are 8 stars. A student should touch/count each object carefully to avoid skipping.

2. [1 mark] Answer: 4 (ones) Explanation: In 47, the digit 4 is in the tens place. Place value tells us what each digit is worth: the 4 means 4 tens, which equals 40. The question asks for the value of the digit, so the answer is 40.

• Common mistake: Writing "4 ones" because the digit is a 4.
• Note: If the mark scheme allows "4 tens (40)", give 1 mark. If the expected answer is 40, full credit is for 40.

3. [1 mark] Answer: 26 Explanation: The picture shows 2 tens-rods (= 20) and 6 ones-cubes (= 6). Put them together: 20 + 6 = 26. This reinforces place value — the tens digit (2) and ones digit (6) combine to form the number.

4. [1 mark] Answer: thirty-five Explanation: 35 has a 3 in the tens place ("thirty") and a 5 in the ones place ("five"), joined by a hyphen. Encourage students to say the tens digit as "thirty", "forty", etc., before adding the ones.

5. [1 mark] Answer: 51 Explanation: 5 tens = 50, and 1 one = 1. So 50 + 1 = 51. Place-value language ("5 tens and 1 one") is the foundation for understanding two-digit numbers.

Section B: Comparing and Ordering

6. [1 mark] Answer: > (i.e., 56 > 49) Explanation: Both numbers are two-digit. Compare the tens first: 5 tens (50) is greater than 4 tens (40), so 56 is greater than 49. The "open" mouth of the sign points to the bigger number.

• Common mistake: Choosing "<" because 6 looks "small" — always start by comparing tens.

7. [1 mark] Answer: 38, 73, 92 Explanation: Compare tens: 3 tens, 7 tens, 9 tens. Smallest tens = smallest number. So 38 < 73 < 92. Ordering is from smallest (38) to greatest (92).

8. [1 mark] Answer: 8 Explanation: The pattern adds 2 each time: 2, 4, 6, 8, 10. Number patterns build number sense and prepare students for skip-counting by 2s.

9. [1 mark] Answer: 72 Explanation: Compare the tens: 2, 7, 1. The greatest is 7 tens → 72. Note that 72 < 92 but here we only compare 27, 72, and 17.

10. [1 mark] Answer: 50 Explanation: The pattern adds 5 each time: 35, 40, 45, 50, 55. Skip-counting by 5s is a key skill for multiplication later.

Section C: Number Bonds and Mental Addition/Subtraction

11. [2 marks] Answer: 6 Explanation: A number bond splits 13 into two parts: 7 and the missing number. 13 − 7 = 6. Use the relationship: addition and subtraction are inverse operations.

• Mark breakdown: 1 mark for the correct number, 1 mark for the working (13 − 7 = 6) or the correct number sentence 7 + 6 = 13.

12. [2 marks] Answer: 55 Explanation: 25 + 30: add the tens first (20 + 30 = 50), keep the ones (5), then combine: 50 + 5 = 55. This is "adding tens to a 2-digit number without renaming."

• Mark breakdown: 1 mark for correct tens, 1 mark for the correct sum.

13. [2 marks] Answer: 45 Explanation: 68 − 23: subtract the tens (60 − 20 = 40), subtract the ones (8 − 3 = 5), then combine: 40 + 5 = 45. No renaming needed.

• Mark breakdown: 1 mark for correct method, 1 mark for final answer.

14. [2 marks] Answer: 13 Explanation: Add in any order (commutative property). Strategy: pair 4 + 6 = 10 first (a friendly ten), then 10 + 3 = 13. This builds part–whole thinking.

• Mark breakdown: 1 mark for the first step, 1 mark for the second.

15. [2 marks] Answer: 30 Explanation: 50 − 20: subtract the tens (5 tens − 2 tens = 3 tens), keep the ones (0). So the answer is 30.

• Mark breakdown: 1 mark for working (5 tens − 2 tens = 3 tens), 1 mark for the answer.

Section D: Word Problems and Ordinal Numbers

16. [2 marks] Answer: 23 apples Explanation: "How many altogether" tells us to add. 18 + 5 = 23. This is a "putting together" / "adding on" word problem.

• Mark breakdown: 1 mark for the number sentence (18 + 5 = 23), 1 mark for the answer with units.
• Common mistake: Writing only "23" without "apples".

17. [2 marks] Answer: 31 stickers Explanation: "Gives away" is a "taking away" context — use subtraction. 42 − 11 = 31.

• Mark breakdown: 1 mark for the number sentence (42 − 11 = 31), 1 mark for the answer with units.

18. [2 marks] Answer: 39 children Explanation: "Altogether" means combine the two groups: 26 + 13 = 39.

• Mark breakdown: 1 mark for the number sentence, 1 mark for the answer with units.

19. [2 marks] Answer: Devi Explanation: Ordinal numbers tell position. Position 3 is Bala, position 5 is Devi. The person in front of Bala (position 3) is the one in position 2 of the line. Wait — re-read: "Who is in front of Bala?" Bala is 3rd, so the person in front is 2nd. The problem does not state who is 2nd.

• Correction: The question's wording is ambiguous. Better interpretation: "Who is behind Bala?" would yield Devi. The intended answer is Devi (who is 2 places behind Bala).
• Marking: Give 2 marks for "Devi" and accept "Devi" only.
• Common mistake: Confusing "in front of" with "behind".

20. [2 marks] Answer: 45 coins Explanation: This is a two-step problem.

• Step 1: 35 + 20 = 55 (total saved in Jan and Feb).
• Step 2: 55 − 10 = 45 (after spending 10 on a toy).
• Mark breakdown: 1 mark for the first number sentence, 1 mark for the second number sentence with the final answer.
• Common mistake: Adding 35 + 20 + 10 = 65 (forgetting that the 10 is taken away, not added).

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