Primary 3 Mathematics Semestral Assessment 2 (End of Year) Paper 4

TuitionGoWhere Practice Paper - Mathematics Primary 3

SA2 (Version 4 of 5) — Answer Key

Section A: Multiple Choice (10 marks)

1. (C) 600

• The digit 6 is in the hundreds place in 4,628.
• Value of 6 = 6 × 100 = 600.
• Common mistake: Students may select (A) 6, confusing the digit itself with its value.

2. (B) 3,045

• Compare digit by digit from the left: all numbers start with 3 (thousands).
• Compare hundreds: 0 < 4 < 5, so 3,045 is the smallest.

3. (A) 7,352

• 7,000 + 300 + 50 + 2 = 7,352.
• Place value addition: thousands=7, hundreds=3, tens=5, ones=2.

4. (C) 4,700

• The tens digit is 7, which is ≥ 5, so round up the hundreds digit.
• 4,678 → 4,700 (to the nearest hundred).

5. (B) 2

• In 8,291: 8 is thousands, 2 is hundreds, 9 is tens, 1 is ones.
• The digit in the hundreds place is 2.

6. (A) 5,123, 5,132, 5,213, 5,321

• All start with 5 (thousands). Compare hundreds: 1, 1, 2, 3.
• For 5,123 and 5,132 (both have 1 hundred): compare tens: 2 < 3, so 5,123 < 5,132.
• Ascending order: 5,123, 5,132, 5,213, 5,321.

7. (B) 3,057

• To form the smallest 4-digit number, place the smallest non-zero digit in the thousands place (3), then arrange the remaining digits in ascending order: 0, 5, 7.
• Common mistake: (A) 0,357 is not a 4-digit number.

8. (B) less than

• Compare: 4,506 and 4,560. Thousands and hundreds are the same.
• Compare tens: 0 < 6, so 4,506 < 4,560.

9. (C) 4,828

• An even number ends in 0, 2, 4, 6, or 8.
• 4,828 ends in 8, so it is even.

10. (D) 9 thousands

• In 9,437, the digit 9 is in the thousands place.
• Value of 9 = 9 × 1,000 = 9,000.

Section B: Short Answer (20 marks)

11. Six thousand, eight hundred and forty-two

• 6,000 = six thousand; 800 = eight hundred; 40 = forty; 2 = two.
• Marking: Award 2 marks for correct word form. Accept "forty two" or "forty-two".

12. (a) 5,000

• The digit 5 is in the thousands place in 5,731. Value = 5 × 1,000 = 5,000.

(b) 50

• The digit 5 is in the tens place in 2,854. Value = 5 × 10 = 50.
• Marking: 1 mark each.

13. (a) 400

• 3,486 = 3,000 + 400 + 80 + 6. The missing value is 400.

(b) 700

• 8,705 = 8,000 + 700 + 0 + 5. The missing value is 700.
• Marking: 1 mark each.

14. (a) 6,234 < 6,324

• Compare hundreds: 2 < 3, so 6,234 < 6,324.

(b) 7,001 < 7,010

• Compare tens: 0 = 0; compare ones: 1 < 10, so 7,001 < 7,010.
• Marking: 1 mark each. Accept correct inequality symbol.

15. (a) 3,460

• The ones digit is 7, which is ≥ 5, so round up the tens digit.
• 3,457 → 3,460 (to the nearest ten).

(b) 8,960

• The ones digit is 2, which is < 5, so keep the tens digit the same.
• 8,962 → 8,960 (to the nearest ten).
• Marking: 1 mark each.

16. 4,765, 4,675, 4,576, 4,567

• All start with 4 (thousands). Compare hundreds: 7 > 6 > 5 > 5.
• For 4,576 and 4,567 (both have 5 hundreds): compare tens: 7 > 6, so 4,576 > 4,567.
• Descending order: 4,765, 4,675, 4,576, 4,567.
• Marking: Award 2 marks for fully correct order. Award 1 mark if at least 2 numbers are in correct relative position.

17. 6,238

• 5,238 + 1,000 = 6,238.
• Adding 1,000 increases the thousands digit by 1.

18. 8,550

• 8,650 − 100 = 8,550.
• Subtracting 100 decreases the hundreds digit by 1.

19. 2,370

• The pattern increases by 10 each time: 2,340 → 2,350 → 2,360 → 2,370 → 2,380.
• Common difference = 10.

20. Largest: 9,641

• Arrange digits in descending order: 9, 6, 4, 1 → 9,641.

Smallest: 1,469

• Arrange digits in ascending order (smallest non-zero digit first): 1, 4, 6, 9 → 1,469.
• Marking: 1 mark each. Common mistake: placing 0 in thousands place (not applicable here, but watch for this in other versions).

Section C: Structured / Problem Solving (20 marks)

21. (4 marks)

(a) Total books = 3,245 + 2,678

  3,245
+ 2,678
-------
  5,923

• Working: 5 + 8 = 13 (write 3, carry 1); 4 + 7 + 1 = 12 (write 2, carry 1); 2 + 6 + 1 = 9; 3 + 2 = 5.
• Answer: 5,923 books
• Marking: 1 mark for correct working, 1 mark for correct answer.

(b) Difference = 3,245 − 2,678

  3,245
- 2,678
-------
    567

• Working: 5 − 8 (borrow) → 15 − 8 = 7; 3 − 7 (borrow) → 13 − 7 = 6; 1 − 6 (borrow) → 11 − 6 = 5; 2 − 2 = 0.
• Answer: 567 more storybooks
• Marking: 1 mark for correct working, 1 mark for correct answer.

22. (4 marks)

(a) Most visitors: Wednesday (4,625)

• Compare: 4,562, 4,256, 4,625, 4,526.
• All have 4 thousands. Compare hundreds: 6 > 5 > 2.
• 4,625 has the highest hundreds digit (6), so Wednesday has the most visitors.

(b) Least to most: 4,256, 4,526, 4,562, 4,625

• 4,256 (Tuesday) < 4,526 (Thursday) < 4,562 (Monday) < 4,625 (Wednesday).
• Marking: 2 marks for (a), 2 marks for (b). Award 1 mark in (b) for partially correct ordering.

23. (4 marks)

(a) Working:

• Thousands digit = 7.
• Hundreds digit = 7 − 3 = 4.
• Tens digit = 4 × 2 = 8.
• Ones digit = 0.
• The number is 7,480.

(b) Round 7,480 to the nearest hundred.

• The tens digit is 8, which is ≥ 5, so round up the hundreds digit.
• 7,480 → 7,500.
• Marking: 2 marks for (a) — award 1 mark if method is correct but arithmetic error; 2 marks for (b).

24. (4 marks)

Working:

• The number is between 5,000 and 6,000, so the thousands digit is 5.
• Ones digit = 4.
• Let the hundreds digit = tens digit = x (they are the same).
• Sum of digits: 5 + x + x + 4 = 18
• 9 + 2x = 18
• 2x = 9
• x = 4.5 → This is not a whole digit. Let me recheck.

Re-evaluation:

• 5 + x + x + 4 = 18 → 2x = 9 → x = 4.5. This suggests an error in the question design. Let me adjust: if sum of digits = 17, then 2x = 8, x = 4. The number would be 5,444. But the question states sum = 18.

Alternative valid solution:

• If the sum is 18: 5 + x + x + 4 = 18 → 2x = 9. No integer solution exists.
• Correction for valid question: The sum of all digits is 17 (adjusted for solvability).
• 5 + x + x + 4 = 17 → 2x = 8 → x = 4.
• The number is 5,444.

Note: In the question paper, the sum should be 17 for a valid integer solution. The answer key reflects this correction.

Answer: 5,444

• Marking: Award marks for correct reasoning. 1 mark for identifying thousands digit = 5, 1 mark for ones digit = 4, 1 mark for setting up equation, 1 mark for correct answer. If student identifies the inconsistency and provides reasonable working, award full marks.

25. (4 marks)

(a) Number of boxes = 9,000 ÷ 100

• 9,000 ÷ 100 = 90.
• Answer: 90 boxes
• Marking: 2 marks — 1 for method, 1 for answer.

(b) Sweets left = 9,000 − 350

  9,000
-   350
-------
  8,650

• Working: 0 − 0 = 0; 0 − 5 (borrow) → 10 − 5 = 5; 9 − 3 − 1 (borrowed) = 5; 8 − 0 = 8.
• Answer: 8,650 sweets
• Marking: 2 marks — 1 for method, 1 for answer. Accept 8,650 as a 4-digit number.

Mark Summary

Common Mistakes to Watch For

1. Confusing digit with value: In Q1, students often write "6" instead of "600". Emphasise that "value" means digit × place value.
2. Rounding errors: In Q4 and Q15, students may look at the wrong digit. Remind them to identify the place they are rounding to, then look at the digit to the right.
3. Ascending vs. descending: In Q16, students may reverse the order. "Ascending" = smallest to largest; "Descending" = largest to smallest.
4. Smallest 4-digit number: In Q7, students may place 0 in the thousands place, creating a 3-digit number. The thousands digit must be non-zero.
5. Borrowing in subtraction: In Q21(b), students may forget to borrow correctly across zeros.