Primary 3 Mathematics Addition Subtraction Quiz

Answer Key: Primary 3 Mathematics Quiz - Addition Subtraction

Total Marks: 40

Section A: Mental Calculation (Questions 1 to 5)

(2 marks each)

1. 340 + 250 = 590

• Method: Add the hundreds: 300 + 200 = 500. Add the tens: 40 + 50 = 90. Total: 500 + 90 = 590.
• Marks: 1 mark for correct working (if shown), 1 mark for correct answer.

2. 780 – 430 = 350

• Method: Subtract the hundreds: 700 – 400 = 300. Subtract the tens: 80 – 30 = 50. Total: 300 + 50 = 350.
• Marks: 1 mark for correct working (if shown), 1 mark for correct answer.

3. 125 + 675 = 800

• Method: Add the ones: 5 + 5 = 10 (write 0, carry 1). Add the tens: 2 + 7 + 1 (carry) = 10 (write 0, carry 1). Add the hundreds: 1 + 6 + 1 (carry) = 8. Answer: 800.
• Marks: 1 mark for correct working (if shown), 1 mark for correct answer.

4. 900 – 350 = 550

• Method: Subtract the hundreds: 900 – 300 = 600. Subtract the tens: 600 – 50 = 550.
• Marks: 1 mark for correct working (if shown), 1 mark for correct answer.

5. 560 + 280 = 840

• Method: Add the tens: 60 + 80 = 140 (write 40, carry 1). Add the hundreds: 5 + 2 + 1 (carry) = 8. Answer: 840.
• Marks: 1 mark for correct working (if shown), 1 mark for correct answer.

Section B: Written Calculation (Questions 6 to 10)

(3 marks each)

6. 2345 + 1678 = 4023

• Method:

    2345
  + 1678
  ------
    4023
  

  Add the ones: 5 + 8 = 13 (write 3, carry 1). Add the tens: 4 + 7 + 1 (carry) = 12 (write 2, carry 1). Add the hundreds: 3 + 6 + 1 (carry) = 10 (write 0, carry 1). Add the thousands: 2 + 1 + 1 (carry) = 4.
• Marks: 1 mark for correct method, 1 mark for correct carrying, 1 mark for correct answer.

7. 5000 – 2345 = 2655

• Method:

    5000
  - 2345
  ------
    2655
  

  Regroup: 5000 = 4 thousands, 9 hundreds, 9 tens, 10 ones. Subtract: 10 – 5 = 5 (ones). 9 – 4 = 5 (tens). 9 – 3 = 6 (hundreds). 4 – 2 = 2 (thousands).
• Marks: 1 mark for correct regrouping, 1 mark for correct subtraction, 1 mark for correct answer.

8. 1256 + 1987 = 3243

• Method:

    1256
  + 1987
  ------
    3243
  

  Add the ones: 6 + 7 = 13 (write 3, carry 1). Add the tens: 5 + 8 + 1 (carry) = 14 (write 4, carry 1). Add the hundreds: 2 + 9 + 1 (carry) = 12 (write 2, carry 1). Add the thousands: 1 + 1 + 1 (carry) = 3.
• Marks: 1 mark for correct method, 1 mark for correct carrying, 1 mark for correct answer.

9. 3500 – 1245 = 2255

• Method:

    3500
  - 1245
  ------
    2255
  

  Regroup: 3500 = 3 thousands, 4 hundreds, 9 tens, 10 ones. Subtract: 10 – 5 = 5 (ones). 9 – 4 = 5 (tens). 4 – 2 = 2 (hundreds). 3 – 1 = 2 (thousands).
• Marks: 1 mark for correct regrouping, 1 mark for correct subtraction, 1 mark for correct answer.

10. 4567 + _______ = 8000

• Method: To find the missing number, subtract: 8000 – 4567 = 3433.

    8000
  - 4567
  ------
    3433
  

  Regroup: 8000 = 7 thousands, 9 hundreds, 9 tens, 10 ones. Subtract: 10 – 7 = 3 (ones). 9 – 6 = 3 (tens). 9 – 5 = 4 (hundreds). 7 – 4 = 3 (thousands).
• Answer: 3433
• Marks: 1 mark for identifying inverse operation, 1 mark for correct subtraction, 1 mark for correct answer.

Section C: Word Problems (Questions 11 to 15)

(3 marks each)

11. $2345 +$1987 = $4332

• Method: Add the amounts: $2345 +$1987 = $4332.
• Answer: $4332
• Marks: 1 mark for identifying addition, 1 mark for correct calculation, 1 mark for correct answer with unit.

12. 4500 kg – 2340 kg = 2160 kg

• Method: Subtract the amount dropped off: 4500 – 2340 = 2160.
• Answer: 2160 kg
• Marks: 1 mark for identifying subtraction, 1 mark for correct calculation, 1 mark for correct answer with unit.

13. 1234 + 987 = 2221

• Method: Add the books sold in the morning and afternoon: 1234 + 987 = 2221.
• Answer: 2221 books
• Marks: 1 mark for identifying addition, 1 mark for correct calculation, 1 mark for correct answer with unit.

14. 2876 – 1234 = 1642

• Method: Subtract the number of boys from the total number of students: 2876 – 1234 = 1642.
• Answer: 1642 girls
• Marks: 1 mark for identifying subtraction, 1 mark for correct calculation, 1 mark for correct answer with unit.

15. 4567 + 2345 = 6912

• Method: Add the apples he already had to the apples he picked: 4567 + 2345 = 6912.
• Answer: 6912 apples
• Marks: 1 mark for identifying addition, 1 mark for correct calculation, 1 mark for correct answer with unit.

Section D: Problem Solving (Questions 16 to 20)

(4 marks each)

16. 23 + 18 = 41 passengers

• Method: Add the passengers who got on at each stop: 23 + 18 = 41.
• Answer: 41 passengers
• Marks: 1 mark for identifying addition, 1 mark for correct calculation, 1 mark for correct answer with unit, 1 mark for clear working.

17. 1250 + 750 = 2000. 2500 – 2000 = 500 packets

• Method: First, find the total number of packets sold: 1250 + 750 = 2000. Then, subtract from the initial amount: 2500 – 2000 = 500.
• Answer: 500 packets
• Marks: 1 mark for correct first step, 1 mark for correct second step, 1 mark for correct answer with unit, 1 mark for clear working.

18. 1234 + 1567 = 2801 cupcakes

• Method: Add the cupcakes sold on Saturday and Sunday: 1234 + 1567 = 2801.
• Answer: 2801 cupcakes
• Marks: 1 mark for identifying addition, 1 mark for correct calculation, 1 mark for correct answer with unit, 1 mark for clear working.

19. $3450 +$2345 = $5795.$5795 – $1234 =$4561

• Method: First, find the total amount raised: $3450 +$2345 = $5795. Then, subtract the amount spent:$5795 – $1234 =$4561.
• Answer: $4561
• Marks: 1 mark for correct first step, 1 mark for correct second step, 1 mark for correct answer with unit, 1 mark for clear working.

20. 5678 – 4322 = 1356

• Method: Subtract the number of toys produced in February from the number produced in January: 5678 – 4322 = 1356.
• Answer: 1356 more toys
• Marks: 1 mark for identifying subtraction, 1 mark for correct calculation, 1 mark for correct answer with unit, 1 mark for clear working.

Common Mistakes to Note:

• For addition, students often forget to carry over when the sum in a column is 10 or more.
• For subtraction, students often forget to regroup when a digit in the top number is smaller than the digit below it.
• In word problems, students may add when they should subtract or vice versa. Encourage them to look for keywords like "altogether" (addition) and "left" (subtraction).
• Remind students to always include units in their answers (e.g., $, kg, books, apples).