Primary 5 Mathematics Whole Numbers Quiz

Primary 5 Mathematics Quiz - Whole Numbers (Answer Key)

Total Marks: 50

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Section A: Multiple Choice Questions (10 marks)

1. Answer: (2) 700 000 [2]

Explanation: In the number 4 728 391, the digit 7 is in the hundred thousands place. Its value is 7 × 100 000 = 700 000.

• Place values from right: ones, tens, hundreds, thousands, ten thousands, hundred thousands, millions.
• Common mistake: Confusing hundred thousands (700 000) with ten thousands (70 000) or millions (7 000 000).

2. Answer: (2) 3 850 000 [2]

Explanation: To round to the nearest ten thousand, look at the thousands digit (7 in 3 847 256). Since 7 ≥ 5, round up the ten thousands digit from 4 to 5. All digits to the right become zero.

• 3 847 256 → 3 850 000
• Common mistake: Rounding to the nearest hundred thousand (3 800 000) or million (4 000 000).

3. Answer: (1) 6 432 589 [2]

Explanation: Add the place values:

• 6 000 000 + 400 000 = 6 400 000
• 6 400 000 + 30 000 = 6 430 000
• 6 430 000 + 2 000 = 6 432 000
• 6 432 000 + 500 = 6 432 500
• 6 432 500 + 80 = 6 432 580
• 6 432 580 + 9 = 6 432 589

4. Answer: (1) 1 275 000 [2]

Explanation: 4 250 × 300 = 4 250 × 3 × 100 = 12 750 × 100 = 1 275 000.

• Multiply by 3 first: 4 250 × 3 = 12 750
• Then multiply by 100 (add two zeros): 1 275 000
• Common mistake: Forgetting zeros (127 500) or adding too many zeros (12 750 000).

5. Answer: (1) 21 400 [2]

Explanation: 8 560 000 ÷ 400 = 8 560 000 ÷ 4 ÷ 100 = 2 140 000 ÷ 100 = 21 400.

• Divide by 4 first: 8 560 000 ÷ 4 = 2 140 000
• Then divide by 100 (remove two zeros): 21 400
• Common mistake: Wrong number of zeros (214 000 or 2 140).

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Section B: Short Answer Questions (20 marks)

6. Seven million, forty-five thousand, six hundred and twenty [2]

Explanation:

• 7 000 000 = Seven million
• 45 000 = Forty-five thousand (not four thousand five hundred)
• 620 = Six hundred and twenty
• Common mistake: Writing "four thousand five hundred" instead of "forty-five thousand" for 045 000.

7. 5 208 400, 5 280 400, 5 802 400, 5 820 400 [2]

Explanation: Compare digit by digit from the left (millions place):

• All have 5 millions.
• Compare hundred thousands: 2, 2, 8, 8 → 5 208 400 and 5 280 400 are smaller.
• For 5 208 400 vs 5 280 400: compare ten thousands (0 vs 8) → 5 208 400 is smaller.
• For 5 802 400 vs 5 820 400: compare ten thousands (0 vs 2) → 5 802 400 is smaller.

8. 3 600 000 [2]

Working: 7 200 × 500 = 7 200 × 5 × 100 = 36 000 × 100 = 3 600 000.

• 7 200 × 5 = 36 000
• 36 000 × 100 = 3 600 000

9. 12 000 [2]

Working: 9 600 000 ÷ 800 = 9 600 000 ÷ 8 ÷ 100 = 1 200 000 ÷ 100 = 12 000.

• 9 600 000 ÷ 8 = 1 200 000
• 1 200 000 ÷ 100 = 12 000

10. 195 000 [2]

Working:

• 4 872 rounded to nearest ten = 4 870
• 39 rounded to nearest ten = 40
• 4 870 × 40 = 4 870 × 4 × 10 = 19 480 × 10 = 194 800 ≈ 195 000 (or accept 194 800)
• Note: Estimation by rounding each to nearest ten gives 4 870 × 40 = 194 800.

11. 61 250 [2]

Working: 2 450 × 25 = 2 450 × 100 ÷ 4 = 245 000 ÷ 4 = 61 250.

• Or: 2 450 × 20 = 49 000; 2 450 × 5 = 12 250; 49 000 + 12 250 = 61 250.

12. 90 000 [2]

Working: 5 400 000 ÷ 60 = 5 400 000 ÷ 6 ÷ 10 = 900 000 ÷ 10 = 90 000.

• 5 400 000 ÷ 6 = 900 000
• 900 000 ÷ 10 = 90 000

13. 0 [2]

Explanation: 6 300 000 = 6 000 000 + 0 + 300 000. The ten thousands and thousands places are both 0.

• Place value breakdown: 6 300 000 = 6 000 000 + 300 000 + 0 + 0 + 0 + 0 + 0
• Common mistake: Writing 30 000 or 3 000 instead of 0.

14. 4 500 499 [2]

Explanation: When rounding to the nearest thousand, numbers from 4 499 500 to 4 500 499 round to 4 500 000. The greatest is 4 500 499.

• Halfway point: 4 500 000 - 500 = 4 499 500 (rounds up)
• Greatest that rounds down: 4 500 000 + 499 = 4 500 499
• 4 500 500 would round up to 4 501 000.

15. $3 700 [2]

Working:

• Cost of 15 chairs = 15 × $320 =$4 800
• Money left = $8 500 -$4 800 = $3 700
• 15 × 320 = 15 × 32 × 10 = 480 × 10 = 4 800

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Section C: Problem Sums (20 marks)

16. 9 680 books [4]

Working:

• Non-fiction books = 3 450 + 2 780 = 6 230
• Total books = 3 450 + 6 230 = 9 680

Mark breakdown:

• 1 mark: Correct non-fiction books (6 230)
• 1 mark: Correct addition for total
• 1 mark: Correct final answer with unit
• 1 mark: Clear working shown

Common mistake: Adding 2 780 to fiction books twice, or finding only non-fiction books.

17. 25 cartons [4]

Working:

• Number of cartons = 4 800 ÷ 24 = 200
• Cartons per truck = 200 ÷ 8 = 25

Mark breakdown:

• 1 mark: Correct total cartons (200)
• 1 mark: Correct division by 8 trucks
• 1 mark: Correct final answer with unit
• 1 mark: Clear working shown

Alternative method: 4 800 ÷ (24 × 8) = 4 800 ÷ 192 = 25

18. 66 bags [4]

Working:

• Total apples = 12 × 36 = 432
• Apples left = 432 - 180 = 252
• Number of bags = 252 ÷ 6 = 42

Wait, let me recalculate: 12 × 36 = 432. 432 - 180 = 252. 252 ÷ 6 = 42 bags.

Correction: Answer is 42 bags, not 66.

Mark breakdown:

• 1 mark: Correct total apples (432)
• 1 mark: Correct apples left (252)
• 1 mark: Correct number of bags (42)
• 1 mark: Clear working shown

19. 800 000 [4]

Working:

• Let smaller number = x, larger number = 5x
• x + 5x = 1 200 000
• 6x = 1 200 000
• x = 200 000
• Larger number = 5 × 200 000 = 1 000 000
• Difference = 1 000 000 - 200 000 = 800 000

Mark breakdown:

• 1 mark: Correct equation setup (6x = 1 200 000)
• 1 mark: Correct smaller number (200 000)
• 1 mark: Correct difference (800 000)
• 1 mark: Clear working shown

Alternative: Difference = 4 parts out of 6 parts = 4/6 × 1 200 000 = 800 000

20. 7 000 seats [4]

Working:

• Total seats = 45 × 280 = 12 600
• Occupied seats = 12 600 - 5 600 = 7 000

Mark breakdown:

• 1 mark: Correct total seats (12 600)
• 1 mark: Correct subtraction for occupied seats
• 1 mark: Correct final answer with unit
• 1 mark: Clear working shown

Calculation check: 45 × 280 = 45 × 28 × 10 = (40 × 28 + 5 × 28) × 10 = (1 120 + 140) × 10 = 1 260 × 10 = 12 600.

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End of Answer Key