Primary 1 Mathematics Addition Subtraction Quiz

Primary 1 Mathematics Quiz - Addition Subtraction: Answer Key

Topic: Addition and Subtraction | Version: 1 of 5 | Total Marks: 40

Teaching notes are written for students new to the topic. Addition means putting together or adding on. Subtraction means taking away, finding what is left, or comparing two amounts.

Answer 1.

Answer: 13 (1 mark)

Method: Start at 7 and count on 6 steps: 8, 9, 10, 11, 12, 13. Or use a near-double: $6 + 6 = 12$, so $7 + 6$ is one more, which is 13. Common mistake: Losing track when crossing 10. Point at each count to stay accurate.

Answer 2.

Answer: 7 (1 mark)

Method: Count back 8 from 15: 14, 13, 12, 11, 10, 9, 8, 7. Or think $8 + \square = 15$, which gives 7. Common mistake: Counting the starting number 15 as one of the 8 steps, giving 8 instead of 7. The first number counted (15) is not counted as a step.

Answer 3.

Answer: 7 (1 mark)

Method: This is a missing-addend question. Ask: "9 plus what makes 16?" Count on from 9 to 16: 10, 11, 12, 13, 14, 15, 16 — that is 7 steps. Check: $9 + 7 = 16$. ✓

Answer 4.

Answer: 12 (1 mark)

Method: Add two numbers first, then the third: $4 + 3 = 7$, then $7 + 5 = 12$. Friendly-pair alternative: $3 + 5 = 8$, then $8 + 4 = 12$. Any order gives the same total because addition order does not matter.

Answer 5.

Answer: 9 (1 mark)

Method (vertical form): Look at the ones: 6 ones − 7 ones cannot be done, so rename 16 as 0 tens and 16 ones (exchange the 1 ten for 10 ones). Then $16 - 7 = 9$. Fact check: $7 + 9 = 16$, so $16 - 7 = 9$. ✓ Common mistake: Writing 11 by subtracting wrongly across the ten. Always check with the inverse addition.

Answer 6.

Answer: 59 (2 marks: M1 method, A1 answer)

Method: Split into tens and ones.

• Tens: $30 + 20 = 50$
• Ones: $4 + 5 = 9$
• Combine: $50 + 9 = 59$

No renaming is needed because the ones (4 + 5 = 9) do not make a new ten.

Answer 7.

Answer: 35 (2 marks: M1 method, A1 answer)

Method: Subtract tens and ones separately.

• Tens: $50 - 20 = 30$
• Ones: $8 - 3 = 5$
• Combine: $30 + 5 = 35$

No renaming is needed since 8 ones can take away 3 ones.

Answer 8.

Answer: 67 (2 marks: M1 method, A1 answer)

Method: Adding 20 means adding 2 tens. Keep the ones digit the same and count tens on: $47 \rightarrow 57 \rightarrow 67$. Key idea: When you add tens, only the tens digit changes; the ones digit stays 7.

Answer 9.

Answer: 6 (2 marks: M1 recognising inverse relation, A1 answer)

Key idea: Addition and subtraction undo each other (they are inverse operations). If $6 + 9 = 15$, then taking 9 away from 15 goes back to where you started: $15 - 9 = 6$. Common mistake: Recomputing from scratch and slipping. Using the given fact is faster and safer.

Answer 10.

Answer: 36 (2 marks: M1 inverse operation, A1 answer)

Method: The question asks: "What number minus 12 leaves 24?" Undo the subtraction by adding: $24 + 12 = 36$. Check: $36 - 12 = 24$. ✓ Common mistake: Computing $24 - 12 = 12$. Remind students that the big number (the whole) comes first in subtraction, so they must build it up by adding.

Answer 11.

Answer: 22 stickers (2 marks: M1 for $14 + 8$, A1 for 22 with unit)

Method: "Altogether" tells us to combine both amounts, so we add.

• Make-ten strategy: $14 + 8 = 14 + 6 + 2 = 20 + 2 = 22$
• Or column addition: ones $4 + 8 = 12$; rename as 1 ten 2 ones; tens $1 + 1 = 2$ → 22

Marking note: Award the method mark even if a small slip occurs in the final total, provided the correct operation $14 + 8$ is shown.

Answer 12.

Answer: 23 marbles (2 marks: M1 for $35 - 12$, A1 for 23 with unit)

Method: Giving marbles away means taking away, so we subtract.

• Tens: $30 - 10 = 20$
• Ones: $5 - 2 = 3$
• Combine: $20 + 3 = 23$

Key idea: "Have left" after giving some away signals subtraction.

Answer 13.

Answer: 17 seashells (3 marks: M1 correct operation $46 - 29$, M1 correct renaming/working, A1 answer with unit)

Method: "How many more" means compare the two amounts by subtracting the smaller from the larger.

• $46 - 29$: the ones give $6 - 9$, which cannot be done, so rename 46 as 3 tens and 16 ones.
• Ones: $16 - 9 = 7$
• Tens: $3 - 2 = 1$
• Answer: 17

Check: $29 + 17 = 46$. ✓ Common mistake: Adding 46 and 29. Adding finds the combined total, not the difference.

Answer 14.

Answer: 59 stamps (3 marks: M1 first step $52 - 18 = 34$, M1 second step $34 + 25$, A1 final answer 59 with unit)

Step 1: Giving away 18 stamps means subtract: $52 - 18$.

• Rename 52 as 4 tens and 12 ones.
• Ones: $12 - 8 = 4$; Tens: $4 - 1 = 3$ → 34 stamps left.

Step 2: Buying 25 more means add: $34 + 25$.

• Ones: $4 + 5 = 9$; Tens: $3 + 2 = 5$ → 59.

Key idea: In a two-step story, perform the operations in the order the events happen: first take away, then add on.

Answer 15.

Answer: 22 counters (2 marks: M1 for $13 + 9$, A1 for 22)

Expected visual: Set A must show 13 red counters (a full ten-frame of 10 plus 3 loose counters); Set B must show 9 blue counters with 1 empty cell. Students read each set by counting.

Method: Count Set A: 10 in the frame plus

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Primary 1 Mathematics Quiz - Addition Subtraction: Answer Key

Topic: Addition and Subtraction | Version: 1 of 5 | Total Marks: 40

Teaching notes are written for students new to the topic. Addition means putting together or adding on. Subtraction means taking away, finding what is left, or comparing two amounts.

Answer 1.

Answer: 13 (1 mark)

Method: Start at 7 and count on 6 steps: 8, 9, 10, 11, 12, 13. Or use a near-double: $6 + 6 = 12$, so $7 + 6$ is one more, which is 13. Common mistake: Losing track when crossing 10. Point at each count to stay accurate.

Answer 2.

Answer: 7 (1 mark)

Method: Count back 8 from 15: 14, 13, 12, 11, 10, 9, 8, 7. Or think $8 + \square = 15$, which gives 7. Common mistake: Counting the starting number 15 as one of the steps, giving 8 instead of 7. Check with $8 + 7 = 15$. ✓

Answer 3.

Answer: 7 (1 mark)

Method: This is a missing-addend question. Ask: "9 plus what makes 16?" Count on from 9 to 16 — that is 7 steps. Check: $9 + 7 = 16$. ✓

Answer 4.

Answer: 12 (1 mark)

Method: Add two numbers first, then the third: $4 + 3 = 7$, then $7 + 5 = 12$. Friendly-pair alternative: $3 + 5 = 8$, then $8 + 4 = 12$. Any order gives the same total because addition order does not matter.

Answer 5.

Answer: 9 (1 mark)

Method (vertical form): 6 ones − 7 ones cannot be done, so rename 16 as 0 tens and 16 ones (exchange the 1 ten for 10 ones). Then $16 - 7 = 9$. Fact check: $7 + 9 = 16$. ✓ Common mistake: Subtracting wrongly across the ten. Always check with the inverse addition.

Answer 6.

Answer: 59 (2 marks: M1 method, A1 answer)

Method: Split into tens and ones.

• Tens: $30 + 20 = 50$
• Ones: $4 + 5 = 9$
• Combine: $50 + 9 = 59$

No renaming is needed because the ones do not make a new ten.

Answer 7.

Answer: 35 (2 marks: M1 method, A1 answer)

Method: Subtract tens and ones separately.

• Tens: $50 - 20 = 30$
• Ones: $8 - 3 = 5$
• Combine: $30 + 5 = 35$

No renaming is needed since 8 ones can take away 3 ones.

Answer 8.

Answer: 67 (2 marks: M1 method, A1 answer)

Method: Adding 20 means adding 2 tens. Keep the ones digit the same and count tens on: $47 \rightarrow 57 \rightarrow 67$. Key idea: When you add tens, only the tens digit changes; the ones digit stays 7.

Answer 9.

Answer: 6 (2 marks: M1 recognising inverse relation, A1 answer)

Key idea: Addition and subtraction undo each other (inverse operations). If $6 + 9 = 15$, then taking 9 away from 15 goes back to the start: $15 - 9 = 6$. Common mistake: Recomputing from scratch and slipping. Using the given fact is faster and safer.

Answer 10.

Answer: 36 (2 marks: M1 inverse operation, A1 answer)

Method: The question asks: "What number minus 12 leaves 24?" Undo the subtraction by adding: $24 + 12 = 36$. Check: $36 - 12 = 24$. ✓ Common mistake: Computing $24 - 12 = 12$. The big number (the whole) comes first in subtraction, so build it up by adding.

Answer 11.

Answer: 22 stickers (2 marks: M1 for $14 + 8$, A1 for 22 with unit)

Method: "Altogether" tells us to combine both amounts, so we add.

• Make-ten strategy: $14 + 8 = 14 + 6 + 2 = 20 + 2 = 22$
• Or column addition: ones $4 + 8 = 12$; rename as 1 ten 2 ones; tens $1 + 1 = 2$ → 22

Marking note: Award the method mark even if a small slip occurs in the final total, provided the correct operation $14 + 8$ is shown.

Answer 12.

Answer: 23 marbles (2 marks: M1 for $35 - 12$, A1 for 23 with unit)

Method: Giving marbles away means taking away, so we subtract.

• Tens: $30 - 10 = 20$
• Ones: $5 - 2 = 3$
• Combine: $20 + 3 = 23$

Key idea: "Have left" after giving some away signals subtraction.

Answer 13.

Answer: 17 seashells (3 marks: M1 correct operation $46 - 29$, M1 correct renaming/working, A1 answer with unit)

Method: "How many more" means compare by subtracting the smaller from the larger.

• $46 - 29$: the ones give $6 - 9$, which cannot be done, so rename 46 as 3 tens and 16 ones.
• Ones: $16 - 9 = 7$
• Tens: $3 - 2 = 1$
• Answer: 17

Check: $29 + 17 = 46$. ✓ Common mistake: Adding 46 and 29. Adding finds the combined total, not the difference.

Answer 14.

Answer: 59 stamps (3 marks: M1 first step $52 - 18 = 34$, M1 second step $34 + 25$, A1 final answer 59 with unit)

Step 1: Giving away 18 stamps means subtract: $52 - 18$.

• Rename 52 as 4 tens and 12 ones.
• Ones: $12 - 8 = 4$; Tens: $4 - 1 = 3$ → 34 stamps left.

Step 2: Buying 25 more means add: $34 + 25$.

• Ones: $4 + 5 = 9$; Tens: $3 + 2 = 5$ → 59.

Key idea: In a two-step story, perform the operations in the order the events happen: first take away, then add on.

Answer 15.

Answer: 22 counters (2 marks: M1 for $13 + 9$, A1 for 22)

Expected visual: Set A must show 13 red counters (a full ten-frame of 10 plus 3 loose counters); Set B must show 9 blue counters with 1 empty cell. Students read each set by counting.

Method: Count Set A: 10 in the frame plus 3 loose = 13. Count Set B: 9 in the frame (1 cell empty). Add: $13 + 9 = 22$. Make-ten strategy: $13 + 9 = 13 + 7 + 2 = 20 + 2 = 22$. Common mistake: Miscounting Set B as 10 because the frame has 10 cells. Remind students that one cell is empty, so only 9 counters are there.

Answer 16.

Answer: 12 (2 marks: M1 for $39 - 27$, A1 for 12)

Method: In a number bond, the whole equals the two parts added together. The whole is 39 and one part is 27, so the missing part is found by subtracting: $39 - 27 = 12$. Check: $27 + 12 = 39$. ✓ Key idea: Whole − known part = missing part. Common mistake: Adding $39 + 27 = 66$. The parts must be smaller than the whole.

Answer 17.

(a) Answer: 65¢ (2 marks: M1 for $40 + 25$, A1 for 65)

Method: Buying both items means adding their prices: $40 + 25 = 65$.

• Tens: $40 + 20 = 60$; Ones: $0 + 5 = 5$ → 65¢ altogether.

(b) Answer: 35¢ (1 mark: A1 for 35)

Method: Change is what is left after paying: $100 - 65 = 35$.

• Rename 100 as 9 tens and 10 ones. Ones: $10 - 5 = 5$; Tens: $9 - 6 = 3$ → 35¢ change. Check: $65 + 35 = 100$. ✓

Answer 18.

Answer: 35 pages (3 marks: M1 correct operation $63 - 28$, M1 correct renaming/working, A1 answer 35 with unit)

Method: "28 pages fewer than Nurul" means Ethan's amount is 28 less than 63, so subtract.

• $63 - 28$: the ones give $3 - 8$, which cannot be done, so rename 63 as 5 tens and 13 ones.
• Ones: $13 - 8 = 5$
• Tens: $5 - 2 = 3$
• Answer: 35

Check: $35 + 28 = 63$. ✓ Common mistake: Adding $63 + 28$. "Fewer than" signals subtraction, not addition.

Answer 19.

Answer: 40 buns (3 marks: M1 first step $68 - 43 = 25$, M1 second step $25 + 15$, A1 final answer 40 with unit)

Step 1: Selling 43 buns means take away: $68 - 43$.

• Tens: $60 - 40 = 20$; Ones: $8 - 3 = 5$ → 25 buns left.

Step 2: Baking 15 more means add on: $25 + 15$.

• Tens: $20 + 10 = 30$; Ones: $5 + 5 = 10$ → $30 + 10 = 40$.

Key idea: Follow the story order: subtract what was sold first, then add what was newly baked. No renaming is needed in either step.

Answer 20.

First box: 39 Second box: 31 (2 marks: M1 for $25 + 14 = 39$, A1 for both boxes correct, ending at 31)

Method: Work along the arrow chain from left to right.

• First arrow (+14): $25 + 14 = 39$. Tens: $20 + 10 = 30$; Ones: $5 + 4 = 9$ → 39.
• Second arrow (−8): $39 - 8 = 31$. Ones: $9 - 8 = 1$; Tens stay 3 → 31.

Check backwards: $31 + 8 = 39$, and $39 - 14 = 25$. ✓ Common mistake: Doing the operations in the wrong direction or applying −8 before +14. Always follow the arrows in order.