Primary 5 Mathematics Multiplication Division Quiz

Primary 5 Mathematics Quiz - Multiplication Division

Answer Key

Total Marks: 40

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Section A: Multiple Choice (2 marks each)

1. B (13 500) [2 marks]

Working: 450 × 30 = 450 × 3 × 10 = 1 350 × 10 = 13 500

Key concept: When multiplying by multiples of 10, count the zeros. 30 has one zero, so multiply 450 × 3 = 1 350, then add one zero.

Common mistake: Forgetting to add the zero from 30, getting 1 350 instead of 13 500.

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2. B (24 × 32 = 768) [2 marks]

Key concept: Division and multiplication are inverse operations. If 768 ÷ 24 = 32, then 24 × 32 = 768 and 32 × 24 = 768.

This follows the relationship: dividend ÷ divisor = quotient, so divisor × quotient = dividend.

Common mistake: Confusing which numbers multiply together — the divisor and quotient give the dividend.

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3. B (50) [2 marks]

Working: 1 250 ÷ 25 = 50

Method: 25 × 50 = 1 250, or use long division: 1 250 ÷ 25 = (1 000 ÷ 25) + (250 ÷ 25) = 40 + 10 = 50

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4. D (300 × 16 = 4 800) [2 marks]

Working:

• A: 600 × 8 = 4 800
• B: 800 × 6 = 4 800
• C: 400 × 12 = 4 800
• D: 300 × 16 = 4 800

All give 4 800! This is a trick question. All answers are equal.

Wait — rechecking: All equal 4 800, so technically all are correct. However, if this were a poorly constructed item, accept D as intended largest if numbers differ slightly.

Actually: 600 × 8 = 4 800; 800 × 6 = 4 800; 400 × 12 = 4 800; 300 × 16 = 4 800.

All are equal. Marking note: Accept any answer since all are equal, but if student identifies this, award full marks for mathematical reasoning. Standard marking: all options A-D are equal, so D is acceptable as the "last" option, or accept any with explanation.

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5. A (60) [2 marks]

Working:

• Total biscuits: 15 × 48 = 720
• Number of bags: 720 ÷ 12 = 60

Or combine: (15 × 48) ÷ 12 = 15 × (48 ÷ 12) = 15 × 4 = 60

Common mistake: Doing 15 × 48 = 720 and stopping, or doing 48 ÷ 12 = 4 then forgetting to multiply by 15.

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Section B: Short Answer (2 marks each)

6. 9 [2 marks]

Working: 3 600 ÷ 400 = 3 600 ÷ (4 × 100) = (3 600 ÷ 100) ÷ 4 = 36 ÷ 4 = 9

Or: 3 600 ÷ 400 = 36 ÷ 4 = 9 (cancel two zeros from both)

Key concept: When dividing numbers ending in zeros, you can cancel equal numbers of zeros from both numbers.

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7. 14 000 [2 marks]

Working: 280 × 50 = 280 × 5 × 10 = 1 400 × 10 = 14 000

Or: 28 × 5 = 140, then add two zeros (one from 280, one from 50) = 14 000

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8. 350 [2 marks]

Working: 4 200 ÷ 60 × 5

Step 1: 4 200 ÷ 60 = 420 ÷ 6 = 70 (cancel one zero) Step 2: 70 × 5 = 350

Order of operations: Division and multiplication have equal precedence, work left to right.

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9. 1 600 [2 marks]

Working: 25 × 16 × 4

Method — use associative property for easier calculation: = (25 × 4) × 16 = 100 × 16 = 1 600

Key concept: Look for friendly number pairs (25 × 4 = 100) to simplify mental calculation. This is much easier than 25 × 16 = 400, then 400 × 4 = 1 600.

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10. 980 pupils [2 marks]

Working: 28 × 35

= 28 × 30 + 28 × 5 = 840 + 140 = 980

Or standard multiplication:

   28
 × 35
 ----
  140  (28 × 5)
  840  (28 × 30)
 ----
  980

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11. 48 marbles [2 marks]

Working: 720 ÷ 15

= 720 ÷ 3 ÷ 5 = 240 ÷ 5 = 48

Or long division: 15 × 48 = 720

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12. 35 boxes, 0 cupcakes left over [2 marks]

Working: 840 ÷ 24

Method: 840 ÷ 24 = 840 ÷ (12 × 2) = (840 ÷ 12) ÷ 2 = 70 ÷ 2 = 35

Or: 24 × 35 = 24 × 30 + 24 × 5 = 720 + 120 = 840 ✓

Since 24 × 35 = 840 exactly, remainder = 0

Marking: 1 mark for correct quotient (35), 1 mark for correct remainder (0).

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13. $60 [2 marks]

Working: $1 080 ÷ 18

Method: 1 080 ÷ 18 = 1 080 ÷ 9 ÷ 2 = 120 ÷ 2 = 60

Or: 18 × 60 = 18 × 6 × 10 = 108 × 10 = 1 080 ✓

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14. 18 lorries [2 marks]

Working: 810 ÷ 45

Method: 810 ÷ 45 = 810 ÷ 9 ÷ 5 = 90 ÷ 5 = 18

Or: 45 × 18 = 45 × 20 - 45 × 2 = 900 - 90 = 810 ✓

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15. 40 m [2 marks]

Working: Area of rectangle = length × breadth

So: breadth = area ÷ length = 2 400 ÷ 60 = 40 m

Check: 60 × 40 = 2 400 ✓

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Section C: Longer Problems (4 marks each)

16. 580 packets [4 marks]

Working:

• Monday: 145 packets
• Tuesday: 3 × 145 = 435 packets [1 mark]
• Wednesday: 435 - 120 = 315 packets [1 mark]
• Total: 145 + 435 + 315 = 580 packets [2 marks]

Or: 145 + (3 × 145) + (3 × 145 - 120) = 145 + 435 + 315 = 580

Marking breakdown:

• Correct Tuesday calculation: 1 mark
• Correct Wednesday calculation: 1 mark
• Correct total with method: 2 marks

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17. 406 storybooks [4 marks]

Working:

• Storybooks on shelves: 8 × 105 = 840 [1 mark]
• Storybooks left over: 2 [1 mark]
• Storybooks remaining: 840 + 2 = 842 [1 mark]
• Storybooks sold: 1 250 - 842 = 408

Wait — let me recheck: 8 × 105 = 840, plus 2 = 842. Sold = 1 250 - 842 = 408

Actually, let me recheck: 8 × 105 = 840. Plus 2 = 842. 1 250 - 842 = 408

408 storybooks [4 marks]

Marking breakdown:

• Find total remaining (8 × 105 + 2): 2 marks
• Correct subtraction to find sold: 2 marks

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18. 250 stamps [4 marks]

Working — using units method:

Step 1: Start with 5 units (whole)

• Gave brother: $\frac{1}{5}$ = 1 unit
• Remainder: 5 - 1 = 4 units

Step 2: From remainder (4 units)

• Gave sister: $\frac{2}{5}$ of 4 units = $\frac{2}{5}$ × 4 = $\frac{8}{5}$ units...

Let's use equal parts (LCM method):

Start: Let total be 5 units

• Brother gets 1 unit
• Remaining: 4 units

Sister gets $\frac{2}{5}$ of remainder = $\frac{2}{5}$ × 4 = $\frac{8}{5}$ units... this gets messy.

Better — use 25 parts (LCM of denominators effectively):

Actually, standard P5 model method:

[5 units] — Brother (1 unit) → [4 units remaining] — Sister ($\frac{2}{5}$ of 4 = ?)

Use 15 units total:

• Brother: 3 units ($\frac{1}{5}$ of 15 = 3)
• Remaining: 12 units
• Sister: $\frac{2}{5}$ of 12 = $\frac{24}{5}$ = not whole

Use 25 units:

• Brother: 5 units ($\frac{1}{5}$ of 25)
• Remaining: 20 units
• Sister: $\frac{2}{5}$ of 20 = 8 units
• Left: 20 - 8 = 12 units

12 units = 120 stamps 1 unit = 10 stamps [2 marks] Total = 25 × 10 = 250 stamps [2 marks]

Marking breakdown:

• Correct model or method to find final fraction remaining: 2 marks
• Correct unit value and total: 2 marks

Common mistake: Taking $\frac{2}{5}$ of original instead of $\frac{2}{5}$ of remainder.

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19. 510 km in 6 hours, 9 hours for 765 km [4 marks]

Part 1: Distance = Speed × Time [1 mark for formula]

• Distance = 85 × 6 = 510 km [1 mark]

Part 2: Time = Distance ÷ Speed [1 mark for formula]

• Time = 765 ÷ 85 = 9 hours [1 mark]

Working check: 85 × 9 = 85 × 10 - 85 = 850 - 85 = 765 ✓

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20. (a) 108 000 cm³ [2 marks]; (b) 9 000 cm³ [2 marks]

Working:

(a) Volume = length × breadth × height = 60 × 45 × 40 = 60 × 45 × 40 = 2 700 × 40 = 108 000 cm³ [2 marks]

Or: 60 × 45 = 2 700; 2 700 × 40 = 108 000

(b) Volume in each container = 108 000 ÷ 12 = 9 000 cm³ [2 marks]

Working: 108 000 ÷ 12 = 108 000 ÷ 4 ÷ 3 = 27 000 ÷ 3 = 9 000

Marking breakdown:

• (a) Correct volume formula and answer: 2 marks (1 for method, 1 for answer)
• (b) Correct division and answer: 2 marks (1 for method, 1 for answer)

Visual reference: The cuboid diagram shows dimensions 60 cm (length), 45 cm (breadth), 40 cm (height). Volume calculation requires multiplying all three dimensions.

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End of Answer Key