Primary 5 Mathematics Whole Numbers Quiz

Primary 5 Mathematics Quiz - Whole Numbers: ANSWER KEY

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Section A: Multiple Choice (2 marks each)

Question 1

Answer: D) 7,000,000

Working and Explanation: The digit 7 is in the millions place. In the number 7,854,231:

• 7 is in the millions place
• 8 is in the hundred-thousands place
• 5 is in the ten-thousands place
• 4 is in the thousands place
• 2 is in the hundreds place
• 3 is in the tens place
• 1 is in the ones place

The place value of 7 = 7 × 1,000,000 = 7,000,000

Common mistake: Choosing B (70,000) confuses the digit position—the 7 is not in the ten-thousands place.

Marking: 2 marks for correct answer.

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Question 2

Answer: A) 7,999,450

Working and Explanation: To round to the nearest thousand, look at the hundreds digit:

• 7,999,450: hundreds digit is 4, so round down → 7,999,000 ❌

Wait—let me recheck. The question asks which rounds to 8,000,000 (nearest thousand, meaning nearest thousand, not nearest million). Actually re-reading: "rounded to the nearest thousand is 8,000,000" — this means the answer should round to 8,000,000 when rounding to nearest thousand.

Let me check each option carefully:

• A) 7,999,450: hundreds digit is 4, rounds to 7,999,000 ❌
• B) 8,000,540: hundreds digit is 5, rounds up to 8,001,000 ❌

Hmm, let me re-interpret: perhaps this means "nearest thousand" where the thousand unit is millions? That would be "nearest million." Re-reading again—the standard interpretation is round to nearest thousand:

Actually, re-checking: to round to 8,000,000 (eight million):

• A) 7,999,450 rounds to 7,999,000 (nearest thousand) or 8,000,000 (nearest million)
• B) 8,000,540 rounds to 8,001,000 (nearest thousand) or 8,000,000 (nearest million)

Given the answer choices, this question likely intends nearest million despite saying "thousand"—or it's testing careful reading.

If nearest million: 7,999,450 → 8,000,000 ✓

Answer: A) 7,999,450 (assuming nearest million, or the question has a wording issue)

Actually, standard interpretation: The most precise reading is that "8,000,000" is the target, so we check which rounds to this. Given 7,999,450 has 999 in the thousands and below, it rounds up at the million level.

Marking: 2 marks for correct answer.

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Question 3

Answer: A) 2,280,000

Working and Explanation: Method 1 (step by step):

• 4,560 × 500 = 4,560 × 5 × 100 = 22,800 × 100 = 2,280,000

Method 2 (using powers of 10):

• 4,560 × 500 = 4,560 × 5 × 10² = 22,800 × 100 = 2,280,000

Key concept: Breaking 500 into 5 × 100 makes mental calculation easier.

Marking: 2 marks for correct answer.

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Question 4

Answer: B) 300

Working and Explanation:

• 12,000 ÷ 40 = 12,000 ÷ (4 × 10) = (12,000 ÷ 10) ÷ 4 = 1,200 ÷ 4 = 300

Or: 12,000 ÷ 40 = 1,200 ÷ 4 = 300 (cancel one zero from both)

Marking: 2 marks for correct answer.

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Question 5

Answer: C) 24

Working and Explanation: Using BODMAS order:

• B: Brackets first — none here
• O: Orders (powers) — none
• D: Division — 16 ÷ 4 = 4
• M: Multiplication — 20 × 3 = 60
• A: Addition — 80 is already there
• S: Subtraction — left to right

Now substitute back: 80 − 60 + 4 = 24

Step by step: 80 − 20 × 3 + 16 ÷ 4 = 80 − 60 + 4 (do × and ÷ first, left to right) = 20 + 4 (do − and + left to right) = 24

Common mistake: Working left to right: 80 − 20 = 60, then 60 × 3 = 180, etc. → wrong answer.

Marking: 2 marks for correct answer.

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Section B: Short Answer (2 marks each)

Question 6

Answer: 6,035,014

Working and Explanation: Break down the words:

• "Six million" = 6,000,000
• "Thirty-five thousand" = 35,000
• "and fourteen" = 14

Add them: 6,000,000 + 35,000 + 14 = 6,035,014

Check: 6,035,014 — places are millions (6), hundred-thousands (0), ten-thousands (3), thousands (5), hundreds (0), tens (1), ones (4). ✓

Marking: 2 marks for correct answer; deduct 1 mark if digits wrong but place value concept shown.

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Question 7

Answer: 8,354,721; 8,534,217; 8,534,712; 8,543,127

Working and Explanation: Compare digit by digit from left (millions place):

• All have 8 in millions place ✓
• Compare hundred-thousands: 5, 5, 3, 5
  • 8,354,721 has 3 → smallest
• Remaining three all have 5 in hundred-thousands: compare ten-thousands
  • 8,534,217 and 8,534,712 have 3; 8,543,127 has 4 → largest
• Compare 8,534,217 and 8,534,712: thousands both 4, hundreds: 2 vs 7
  • 2 < 7, so 8,534,217 < 8,534,712

Final order: 8,354,721; 8,534,217; 8,534,712; 8,543,127

Marking: 2 marks for fully correct order; 1 mark if one number misplaced.

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Question 8

Answer: 7,460,000

Working and Explanation: Round 7,459,832 to nearest ten thousand:

• Locate ten thousands place: 7,459,832 — the 9 is in the thousands place (the digit to the right of ten thousands)
• Actually: 7,459,832 — ten thousands digit is 5, thousands digit is 9

To round to nearest ten thousand, look at the thousands digit:

• Thousands digit is 9, which is ≥ 5, so round UP the ten thousands digit (5) by 1 → 6

Replace digits to the right with zeros: 7,460,000

Marking: 2 marks for correct answer.

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Question 9

Answer: 125,000

Working and Explanation: Use associative property to make calculation easier: 125 × 40 × 25 = 125 × (40 × 25) = 125 × 1,000 = 125,000

Or: 125 × 25 × 40 = 3,125 × 40 = 125,000

Key concept: 125 × 8 = 1,000, and 40 = 5 × 8, so 125 × 40 = 125 × 5 × 8 = 625 × 8 = 5,000, then × 25... actually the first method is cleaner.

Actually simpler: 125 × 40 = 5,000; 5,000 × 25 = 125,000

Marking: 2 marks for correct answer with working shown.

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Question 10

Answer: 1,350

Working and Explanation: 810,000 ÷ 600 = 810,000 ÷ (6 × 100) = (810,000 ÷ 100) ÷ 6 = 8,100 ÷ 6 = 1,350

Or cancel two zeros: 8,100 ÷ 6 = 1,350

Check: 1,350 × 600 = 1,350 × 6 × 100 = 8,100 × 100 = 810,000 ✓

Marking: 2 marks for correct answer.

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Question 11

Answer: 30

Working and Explanation: Using BODMAS: 36 + 24 ÷ 6 × 2 − 10

Step 1: Division and multiplication (left to right)

• 24 ÷ 6 = 4
• 4 × 2 = 8

Step 2: Addition and subtraction (left to right)

• 36 + 8 = 44
• 44 − 10 = 30

Common mistake: 36 + 24 = 60, then 60 ÷ 6 = 10, etc. → wrong.

Marking: 2 marks for correct answer.

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Question 12

Answer: 34

Working and Explanation: (48 − 18) ÷ 5 + 7 × 4

Step 1: Brackets first

• (48 − 18) = 30

Step 2: Division and multiplication (left to right)

• 30 ÷ 5 = 6
• 7 × 4 = 28

Step 3: Addition

• 6 + 28 = 34

Marking: 2 marks for correct answer.

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Question 13

Answer: 56

Working and Explanation: ? × 1,000 = 56,000

To find the missing number, divide both sides by 1,000: ? = 56,000 ÷ 1,000 = 56

Key concept: Dividing by 1,000 shifts digits 3 places to the right.

Marking: 2 marks for correct answer.

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Question 14

Answer: 3

Working and Explanation: When dividing by 10, the remainder is always the ones digit of the original number.

458,293 ÷ 10 = 45,829 remainder 3

Or: Any number = (multiple of 10) + (ones digit), so remainder is the ones digit, which is 3.

Marking: 2 marks for correct answer.

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Question 15

Answer: 4,500,000

Working and Explanation: Rounding to nearest million: 5,000,000

For a number to round up to 5,000,000, it must be at least halfway between 4,000,000 and 5,000,000.

The halfway point is 4,500,000.

Numbers from 4,500,000 to 5,499,999 round to 5,000,000 (nearest million).

Smallest possible value: 4,500,000

Marking: 2 marks for correct answer.

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Section C: Problem Solving (4 marks each)

Question 16

Answer: 76,750 toy cars

Working and Explanation: This is a two-part multiplication problem.

First period (15 days):

• 3,250 × 15 = 3,250 × 10 + 3,250 × 5
• = 32,500 + 16,250
• = 48,750 toy cars

Second period (10 days):

• 2,800 × 10 = 28,000 toy cars

Total:

• 48,750 + 28,000 = 76,750 toy cars

Marking breakdown:

• 1 mark: Correct calculation for first period (48,750)
• 1 mark: Correct calculation for second period (28,000)
• 1 mark: Correct addition to find total
• 1 mark: Correct final answer with units

Common mistake: Forgetting to multiply by the number of days; just adding 3,250 + 2,800.

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Question 17

Answer: 680 girls

Working and Explanation: Step 1: Find number of children

• Total seats = 4,500
• Adults = 2,800
• Children = 4,500 − 2,800 = 1,700

Step 2: Use the ratio (children only)

• Ratio of boys to girls = 2 : 3 (since for every 5 children, 2 are boys, so 3 are girls)
• Wait: re-read: "For every 5 children, 2 were boys" → boys : girls = 2 : 3

Actually: For every 5 children, 2 are boys, so 5 − 2 = 3 are girls. Ratio boys : girls = 2 : 3

Total parts = 2 + 3 = 5 parts

Step 3: Find number of girls

• 1 part = 1,700 ÷ 5 = 340
• Girls = 3 parts = 340 × 3 = 1,020

Let me recheck: 2 + 3 = 5, yes. 1,700 ÷ 5 = 340. Girls = 3 × 340 = 1,020

Wait—let me re-verify my calculation: 340 × 3 = 1,020. And 340 × 2 = 680 boys. 680 + 1,020 = 1,700 ✓

Answer: 1,020 girls

Marking breakdown:

• 1 mark: Correct number of children (1,700)
• 1 mark: Correct interpretation of ratio (boys:girls = 2:3)
• 1 mark: Correct value of one part (340)
• 1 mark: Correct final answer with units

Common mistake: Using 2:5 as the ratio for girls instead of 3:5, or confusing total ratio parts.

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Question 18

Answer: 150 small boxes

Working and Explanation: Step 1: Find apples in large boxes

• 120 large boxes × 80 apples each = 9,600 apples

Step 2: Find remaining apples for small boxes

• Total apples = 15,600
• Remaining = 15,600 − 9,600 = 6,000 apples

Step 3: Find number of small boxes

• 6,000 ÷ 40 = 150 small boxes

Check: (120 × 80) + (150 × 40) = 9,600 + 6,000 = 15,600 ✓

Marking breakdown:

• 1 mark: Correct apples in large boxes (9,600)
• 1 mark: Correct remaining apples (6,000)
• 1 mark: Correct division to find small boxes
• 1 mark: Correct final answer with units

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Question 19

Answer: 140

Working and Explanation: 120 ÷ (8 − 3) × (15 − 9) − 24 ÷ 6

Step 1: Brackets

• (8 − 3) = 5
• (15 − 9) = 6

Expression becomes: 120 ÷ 5 × 6 − 24 ÷ 6

Step 2: Division and multiplication (left to right)

• 120 ÷ 5 = 24
• 24 × 6 = 144
• 24 ÷ 6 = 4

Step 3: Subtraction

• 144 − 4 = 140

Marking breakdown:

• 1 mark: Correct bracket evaluation (5 and 6)
• 1 mark: Correct division/multiplication sequence
• 1 mark: Correct intermediate values
• 1 mark: Correct final answer

Common mistake: Doing 5 × 6 = 30 first (wrong—÷ and × are equal priority, left to right); or getting 120 ÷ 30 = 4.

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Question 20

Answer: 750,000

Working and Explanation: This is a "before-and-after" or unit model problem.

Given: Larger number = 4 × smaller number, and sum = 1,250,000

Using units:

• Smaller number = 1 unit
• Larger number = 4 units
• Total = 5 units = 1,250,000

Step 1: Find 1 unit

• 1 unit = 1,250,000 ÷ 5 = 250,000

Step 2: Find both numbers

• Smaller number = 250,000
• Larger number = 4 × 250,000 = 1,000,000

Step 3: Find difference

• Difference = 1,000,000 − 250,000 = 750,000

Or: Difference = 4 units − 1 unit = 3 units = 3 × 250,000 = 750,000

Check: 250,000 + 1,000,000 = 1,250,000 ✓

Marking breakdown:

• 1 mark: Correct total units (5) and value of 1 unit (250,000)
• 1 mark: Correct identification of both numbers
• 1 mark: Correct method for finding difference
• 1 mark: Correct final answer

Common mistake: Finding the two numbers but then adding instead of subtracting; or using 4 − 1 = 3 but not multiplying by the unit value.