Primary 4 Mathematics Addition Subtraction Quiz

Answer Key: Primary 4 Mathematics Quiz - Addition Subtraction

Total Marks: 40

Section A: Multiple Choice Questions (5 marks)

1. (A) 6 899

• Marks: 1
• Explanation: To find the sum, add the two numbers: 4 528 + 2 371 = 6 899. Start from the ones place: 8 + 1 = 9, then tens: 2 + 7 = 9, then hundreds: 5 + 3 = 8, then thousands: 4 + 2 = 6. So the answer is 6 899.
• Common mistake: Students may forget to carry over if there is a carry, but here no carrying is needed.

2. (A) 4 544

• Marks: 1
• Explanation: Subtract 3 456 from 8 000. Since 8 000 has zeros in the hundreds, tens, and ones places, we need to regroup. 8 000 = 7 999 + 1. So 8 000 - 3 456 = 7 999 - 3 456 + 1 = 4 543 + 1 = 4 544. Alternatively, subtract directly with borrowing: 8 000 - 3 456 = 4 544.
• Common mistake: Students may forget to borrow correctly when subtracting from a number with zeros.

3. (A) 1 172

• Marks: 1
• Explanation: The baker starts with 2 450 eggs and uses 1 278. So we subtract: 2 450 - 1 278 = 1 172. Borrow from the hundreds: 4 hundreds becomes 3 hundreds, and 5 tens becomes 15 tens. Then subtract: 15 - 7 = 8 in tens, 3 - 2 = 1 in hundreds, 2 - 1 = 1 in thousands, and 0 in ones: 0 - 8 needs borrowing from tens, so 10 - 8 = 2 in ones.
• Common mistake: Students may add instead of subtract because the word "uses" might be misinterpreted.

4. (A) 5 632

• Marks: 1
• Explanation: The expanded form 5 000 + 600 + 30 + 2 means 5 thousands, 6 hundreds, 3 tens, and 2 ones. So the number is 5 632.
• Common mistake: Students may misplace the digits, e.g., writing 5 362 (3 hundreds, 6 tens) instead of 5 632.

5. (B) 6 300

• Marks: 1
• Explanation: Add 3 500 and 2 800. 3 500 + 2 800 = 3 500 + 2 000 + 800 = 5 500 + 800 = 6 300. Alternatively, 35 hundreds + 28 hundreds = 63 hundreds = 6 300.
• Common mistake: Students may forget to carry the thousand: 3 500 + 2 800 = 6 300, not 5 300.

Section B: Short Answer Questions (20 marks)

6. Sum of 12 456 and 8 789 = 21 245

• Marks: 2 (1 mark for correct method, 1 mark for correct answer)
• Explanation: Add the two numbers: 12 456 + 8 789. Start from the ones: 6 + 9 = 15, write 5, carry 1 to tens. Tens: 5 + 8 + 1 (carry) = 14, write 4, carry 1 to hundreds. Hundreds: 4 + 7 + 1 (carry) = 12, write 2, carry 1 to thousands. Thousands: 2 + 8 + 1 (carry) = 11, write 1, carry 1 to ten thousands. Ten thousands: 1 + 0 + 1 (carry) = 2. So the sum is 21 245.
• Common mistake: Forgetting to add the carry-over digits.

7. 14 203 - 5 678 = 8 525

• Marks: 2 (1 mark for correct method, 1 mark for correct answer)
• Explanation: Subtract 5 678 from 14 203. Borrow from the thousands: 14 203 becomes 13 203 + 1 000 = 13 203 + 1 000. Then subtract: 13 203 - 5 678 = 7 525. But we borrowed 1 000, so we need to add it back? No, let's do it step by step: 14 203 - 5 678. Ones: 3 - 8, borrow from tens (0 tens, so borrow from hundreds: 2 hundreds becomes 1 hundred, 0 tens becomes 10 tens, then borrow 1 ten: 10 tens becomes 9 tens, 3 ones becomes 13 ones). 13 - 8 = 5. Tens: 9 - 7 = 2. Hundreds: 1 - 6, borrow from thousands: 4 thousands becomes 3 thousands, 1 hundred becomes 11 hundreds. 11 - 6 = 5. Thousands: 3 - 5, borrow from ten thousands: 1 ten thousand becomes 0, 3 thousands becomes 13 thousands. 13 - 5 = 8. Ten thousands: 0 - 0 = 0. So answer is 8 525.
• Common mistake: Incorrect borrowing, especially when zeros are involved.

8. Total packets = 3 250 + 4 680 = 7 930

• Marks: 2 (1 mark for correct method, 1 mark for correct answer)
• Explanation: Add the two numbers: 3 250 + 4 680 = 7 930. Ones: 0 + 0 = 0. Tens: 5 + 8 = 13, write 3, carry 1. Hundreds: 2 + 6 + 1 = 9. Thousands: 3 + 4 = 7. So total is 7 930 packets.
• Common mistake: Forgetting to carry the 1 from the tens place.

9. Chickens left = 9 000 - 3 475 = 5 525

• Marks: 2 (1 mark for correct method, 1 mark for correct answer)
• Explanation: Subtract 3 475 from 9 000. Since 9 000 has zeros, we borrow: 9 000 = 8 999 + 1. So 9 000 - 3 475 = 8 999 - 3 475 + 1 = 5 524 + 1 = 5 525.
• Common mistake: Forgetting to add the 1 back after borrowing.

10. Number to add = 10 000 - 6 543 = 3 457

• Marks: 2 (1 mark for correct method, 1 mark for correct answer)
• Explanation: To find the number that must be added to 6 543 to get 10 000, we subtract: 10 000 - 6 543 = 3 457. This is the inverse operation of addition.
• Common mistake: Students may add instead of subtract.

11. Larger number = 4 567 + 2 345 = 6 912

• Marks: 2 (1 mark for correct method, 1 mark for correct answer)
• Explanation: The difference between two numbers is 2 345, and the smaller number is 4 567. The larger number is the smaller number plus the difference: 4 567 + 2 345 = 6 912.
• Common mistake: Students may subtract instead of add.

12. More girls = 1 380 - 1 250 = 130

• Marks: 2 (1 mark for correct method, 1 mark for correct answer)
• Explanation: To find how many more girls than boys, subtract the number of boys from the number of girls: 1 380 - 1 250 = 130.
• Common mistake: Students may add instead of subtract.

13. Sand left = 4 500 - 2 750 = 1 750 kg

• Marks: 2 (1 mark for correct method, 1 mark for correct answer)
• Explanation: Subtract the amount dropped off from the initial amount: 4 500 - 2 750 = 1 750 kg.
• Common mistake: Forgetting to include the unit (kg) in the answer.

14. More pages = 320 - 95 = 225

• Marks: 2 (1 mark for correct method, 1 mark for correct answer)
• Explanation: Subtract the number of pages in the magazine from the number of pages in the book: 320 - 95 = 225.
• Common mistake: Students may add instead of subtract.

15. Total toys = 5 600 + 6 850 = 12 450

• Marks: 2 (1 mark for correct method, 1 mark for correct answer)
• Explanation: Add the number of toys produced in January and February: 5 600 + 6 850 = 12 450.
• Common mistake: Forgetting to carry over when adding.

Section C: Problem Sums (15 marks)

16. Boxes left = 8 500 - 3 275 - 2 890 = 2 335

• Marks: 3 (1 mark for correct method, 1 mark for correct working, 1 mark for correct answer)
• Explanation: First, find the total number of boxes delivered: 3 275 + 2 890 = 6 165. Then subtract from the initial amount: 8 500 - 6 165 = 2 335. Alternatively, subtract each delivery separately: 8 500 - 3 275 = 5 225, then 5 225 - 2 890 = 2 335.
• Common mistake: Students may forget to add the two deliveries together before subtracting.

17. Passengers now = 1 250 - 678 + 345 = 917

• Marks: 3 (1 mark for correct method, 1 mark for correct working, 1 mark for correct answer)
• Explanation: First, subtract the passengers who get off: 1 250 - 678 = 572. Then add the new passengers: 572 + 345 = 917.
• Common mistake: Students may add the passengers who get off instead of subtracting.

18. Books now = 12 500 + 2 350 - 1 800 = 13 050

• Marks: 3 (1 mark for correct method, 1 mark for correct working, 1 mark for correct answer)
• Explanation: First, add the new books: 12 500 + 2 350 = 14 850. Then subtract the old books removed: 14 850 - 1 800 = 13 050.
• Common mistake: Students may subtract the new books instead of adding.

19. Plants left = 3 450 + 2 680 - 1 200 = 4 930

• Marks: 3 (1 mark for correct method, 1 mark for correct working, 1 mark for correct answer)
• Explanation: First, find the total number of plants: 3 450 + 2 680 = 6 130. Then subtract the plants given away: 6 130 - 1 200 = 4 930.
• Common mistake: Students may forget to add the two types of plants together first.

20. Rice left = 10 000 - 3 250 - 4 780 = 1 970 kg

• Marks: 3 (1 mark for correct method, 1 mark for correct working, 1 mark for correct answer)
• Explanation: First, find the total amount of rice sold: 3 250 + 4 780 = 8 030 kg. Then subtract from the initial amount: 10 000 - 8 030 = 1 970 kg. Alternatively, subtract each day's sales: 10 000 - 3 250 = 6 750, then 6 750 - 4 780 = 1 970.
• Common mistake: Forgetting to include the unit (kg) in the answer.

Marking Notes:

• For Section A, only the final circled answer is marked.
• For Sections B and C, award method marks even if the final answer is incorrect, provided the working shows understanding of the correct operation.
• Deduct 0.5 marks for missing or incorrect units where applicable.
• For multi-step problems, award marks for each correct step.