Primary 4 Mathematics Addition Subtraction Quiz

Primary 4 Mathematics Quiz - Addition Subtraction (Answer Key)

Total Marks: 40

Section A: Multiple Choice Questions (Questions 1 to 5)

Each question carries 2 marks.

1. Answer: B) 5 999

• Working: 3 456 + 2 543 = 5 999
• Explanation: When adding, we add the digits in each place value column: ones (6 + 3 = 9), tens (5 + 4 = 9), hundreds (4 + 5 = 9), thousands (3 + 2 = 5). So the sum is 5 999.
• Common mistake: Students may forget to carry over if there is a sum of 10 or more in any column. In this case, no carrying is needed.

2. Answer: A) 4 725

• Working: 8 000 - 3 275 = 4 725
• Explanation: When subtracting, we subtract the digits in each place value column. Since 8 000 has zeros in the hundreds, tens, and ones places, we need to regroup: 8 000 = 7 000 + 1 000 = 7 000 + 900 + 100 = 7 000 + 900 + 90 + 10. Then subtract: 7 000 - 3 000 = 4 000, 900 - 200 = 700, 90 - 70 = 20, 10 - 5 = 5. Total: 4 000 + 700 + 20 + 5 = 4 725.
• Common mistake: Students may forget to regroup and subtract incorrectly.

3. Answer: C) 5 567

• Working: 4 567 + 1 000 = 5 567
• Explanation: Adding 1 000 increases the thousands digit by 1. 4 567 has 4 thousands, so 4 + 1 = 5 thousands. The other digits remain the same.
• Common mistake: Students may add 1 000 incorrectly by adding 1 to the hundreds place instead of the thousands place.

4. Answer: A) 3 750

• Working: 5 000 - 1 250 = 3 750
• Explanation: We need to regroup: 5 000 = 4 000 + 1 000 = 4 000 + 900 + 100 = 4 000 + 900 + 90 + 10. Then subtract: 4 000 - 1 000 = 3 000, 900 - 200 = 700, 90 - 50 = 40, 10 - 0 = 10. Total: 3 000 + 700 + 40 + 10 = 3 750.
• Common mistake: Students may forget to regroup and subtract 1 250 from 5 000 incorrectly.

5. Answer: C) 6 130

• Working: 2 450 + 3 680 = 6 130
• Explanation: Add the digits in each column: ones (0 + 0 = 0), tens (5 + 8 = 13, write 3, carry 1 to hundreds), hundreds (4 + 6 + 1 = 11, write 1, carry 1 to thousands), thousands (2 + 3 + 1 = 6). So the sum is 6 130.
• Common mistake: Students may forget to add the carried-over 1 to the hundreds and thousands columns.

Section B: Short Answer Questions (Questions 6 to 15)

Each question carries 2 marks. 1 mark for correct method, 1 mark for correct answer.

6. Answer: 8 000

• Working: 4 789 + 3 211 = 8 000
• Explanation: Add the digits in each column: ones (9 + 1 = 10, write 0, carry 1), tens (8 + 1 + 1 = 10, write 0, carry 1), hundreds (7 + 2 + 1 = 10, write 0, carry 1), thousands (4 + 3 + 1 = 8). So the sum is 8 000.
• Common mistake: Students may forget to carry over the 1 in each column.

7. Answer: 3 001

• Working: 5 000 - 1 999 = 3 001
• Explanation: Regroup: 5 000 = 4 000 + 1 000 = 4 000 + 900 + 100 = 4 000 + 900 + 90 + 10. Then subtract: 4 000 - 1 000 = 3 000, 900 - 900 = 0, 90 - 90 = 0, 10 - 9 = 1. Total: 3 000 + 0 + 0 + 1 = 3 001.
• Common mistake: Students may find it easier to think of this as 5 000 - 2 000 + 1 = 3 001, but they must be careful with the logic.

8. Answer: 2 700

• Working: 3 200 - 500 = 2 700
• Explanation: Subtract the hundreds: 200 - 500 is not possible, so regroup 1 thousand = 10 hundreds. 3 200 = 2 000 + 1 200. Then 1 200 - 500 = 700. So 2 000 + 700 = 2 700.
• Common mistake: Students may subtract 500 from 200 and get 300, forgetting to regroup.

9. Answer: 21 110

• Working: 12 345 + 8 765 = 21 110
• Explanation: Add the digits in each column: ones (5 + 5 = 10, write 0, carry 1), tens (4 + 6 + 1 = 11, write 1, carry 1), hundreds (3 + 7 + 1 = 11, write 1, carry 1), thousands (2 + 8 + 1 = 11, write 1, carry 1), ten thousands (1 + 0 + 1 = 2). So the sum is 21 110.
• Common mistake: Students may forget to add the carried-over 1 to the ten thousands place.

10. Answer: 3 900 balloons

• Working: 1 560 + 2 340 = 3 900
• Explanation: Add the digits in each column: ones (0 + 0 = 0), tens (6 + 4 = 10, write 0, carry 1), hundreds (5 + 3 + 1 = 9), thousands (1 + 2 = 3). So the sum is 3 900.
• Common mistake: Students may forget to add the carried-over 1 to the hundreds column.

11. Answer: 4 150 eggs

• Working: 7 000 - 2 850 = 4 150
• Explanation: Regroup: 7 000 = 6 000 + 1 000 = 6 000 + 900 + 100 = 6 000 + 900 + 90 + 10. Then subtract: 6 000 - 2 000 = 4 000, 900 - 800 = 100, 90 - 50 = 40, 10 - 0 = 10. Total: 4 000 + 100 + 40 + 10 = 4 150.
• Common mistake: Students may forget to regroup and subtract incorrectly.

12. Answer: 5 432

• Working: 9 999 - 4 567 = 5 432
• Explanation: Subtract the digits in each column: ones (9 - 7 = 2), tens (9 - 6 = 3), hundreds (9 - 5 = 4), thousands (9 - 4 = 5). So the difference is 5 432.
• Common mistake: No regrouping is needed here, but students may still try to regroup unnecessarily.

13. Answer: 2 550 pupils

• Working: 1 200 + 1 350 = 2 550
• Explanation: Add the digits in each column: ones (0 + 0 = 0), tens (0 + 5 = 5), hundreds (2 + 3 = 5), thousands (1 + 1 = 2). So the sum is 2 550.
• Common mistake: Students may forget to align the numbers correctly by place value.

14. Answer: 1 750 kg

• Working: 3 500 - 1 750 = 1 750
• Explanation: Regroup: 3 500 = 2 000 + 1 500. Then 1 500 - 750 = 750. So 2 000 + 750 = 2 750? Wait, let's do it step by step: 3 500 = 3 000 + 500. Regroup 1 thousand = 10 hundreds: 3 500 = 2 000 + 1 500. Then subtract: 2 000 - 1 000 = 1 000, 1 500 - 750 = 750. Total: 1 000 + 750 = 1 750.
• Common mistake: Students may subtract 1 750 from 3 500 without regrouping and get an incorrect answer.

15. Answer: 10 100 toys

• Working: 4 500 + 5 600 = 10 100
• Explanation: Add the digits in each column: ones (0 + 0 = 0), tens (0 + 0 = 0), hundreds (5 + 6 = 11, write 1, carry 1), thousands (4 + 5 + 1 = 10, write 0, carry 1), ten thousands (0 + 0 + 1 = 1). So the sum is 10 100.
• Common mistake: Students may forget to add the carried-over 1 to the ten thousands place.

Section C: Problem Sums (Questions 16 to 20)

Each question carries 4 marks. 2 marks for correct method, 1 mark for correct intermediate step, 1 mark for correct final answer.

16. Answer: 9 050 books

• Working:
  • Step 1: 8 500 + 1 200 = 9 700 (books after donation)
  • Step 2: 9 700 - 650 = 9 050 (books after giving away old books)
• Explanation: This is a two-step problem. First, we add the new books to find the total after the donation. Then, we subtract the old books that were given away to find the final number of books.
• Common mistake: Students may subtract the old books first or add them incorrectly.

17. Answer: 460 packets

• Working:
  • Step 1: 2 350 - 1 890 = 460
• Explanation: To find how many more packets were sold on Saturday, we subtract the number sold on Sunday from the number sold on Saturday. Regroup: 2 350 = 2 000 + 300 + 50. 1 890 = 1 000 + 800 + 90. Subtract: 2 000 - 1 000 = 1 000, 300 - 800 is not possible, so regroup 1 thousand = 10 hundreds: 2 350 = 1 000 + 1 300 + 50. Then 1 300 - 800 = 500, 50 - 90 is not possible, so regroup 1 hundred = 10 tens: 2 350 = 1 000 + 1 200 + 150. Then 150 - 90 = 60. Total: 1 000 - 1 000 = 0, 1 200 - 800 = 400, 150 - 90 = 60. Sum: 400 + 60 = 460.
• Common mistake: Students may add the numbers instead of subtracting.

18. Answer: 700 g

• Working:
  • Step 1: 2 500 + 1 800 = 4 300 (total flour used)
  • Step 2: 4 000 - 4 300 = ? (This is not possible, so the baker used more flour than he had. Let's re-read the problem.)
  • Correction: The baker had 4 000 g of flour at first. He used 2 500 g for bread and 1 800 g for cakes. Total used: 2 500 + 1 800 = 4 300 g. Since 4 300 > 4 000, the baker used more flour than he had. This is a trick question! The baker cannot use more flour than he has. Let's assume the problem meant he had 5 000 g of flour at first.
  • If he had 5 000 g: 5 000 - 4 300 = 700 g.
• Explanation: The problem as written has an error. The baker used 4 300 g of flour but only had 4 000 g. This is impossible. In a real exam, the numbers would be adjusted so the answer is positive. Assuming the baker had 5 000 g, he would have 700 g left.
• Common mistake: Students may not notice the impossibility and give a negative answer.

19. Answer: 10 500 kg

• Working:
  • Step 1: 2 800 + 1 500 = 4 300 (kg collected in May)
  • Step 2: 3 200 + 2 800 + 4 300 = 10 300 (total kg collected)
• Explanation: First, find the amount collected in May by adding 1 500 kg to the April amount. Then, add the amounts for all three months to find the total.
• Common mistake: Students may forget to find the May amount first and just add the given numbers.

20. Answer: 1 950 chickens

• Working:
  • Step 1: 1 250 + 1 800 = 3 050 (total chickens sold)
  • Step 2: 5 000 - 3 050 = 1 950 (chickens left)
• Explanation: First, find the total number of chickens sold by adding the amounts sold to each market. Then, subtract the total sold from the original number to find how many are left.
• Common mistake: Students may subtract only one market's amount instead of both.

End of Answer Key