Addition and subtraction within 20 – Year 1 maths test answers to download as PDF

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1. Answer to Question 1 (4 marks)

   1. Start at 5 and count on 4: 6, 7, 8, 9. So 5 + 4 = 9. (1 mark)
   2. Use a near double: 7 + 7 = 14, and 8 is one more than 7, so 8 + 7 = 15. (1 mark)
   3. Count on from 6 to 10: 7, 8, 9, 10. That is 4 steps, so the missing number is 4. (1 mark)
   4. This is a double: 9 + 9 = 18. (1 mark)

2. Answer to Question 2 (4 marks)

   1. Count back 4 from 9: 8, 7, 6, 5. So 9 − 4 = 5. (1 mark)
   2. Take 5 to reach 10, then take 1 more: 15 − 6 = 9. (1 mark)
   3. Taking 10 from 20 leaves 10. We take 8, which is 2 less than 10, so 2 more is left: 20 − 8 = 12. (1 mark)
   4. Use the bond 3 + 7 = 10, so 10 − 7 = 3. (1 mark)

3. Answer to Question 3 (4 marks)

   1. Adding works in any order, so swapping the numbers gives 6 + 7 = 13. (1 mark)
   2. Take 7 away from the whole, 13, and the other part is left: 13 − 7 = 6. (1 mark)
   3. Take the other part away from 13: 13 − 6 = 7. (1 mark)
   4. No. For subtraction the order matters: we start with the whole, 13, and take a part away. We cannot take 13 away from 6 because 6 is the smaller number. (1 mark: no and the idea that 13 cannot come out of 6)

4. Answer to Question 4 (4 marks)

   1. Count the jumps on the number line, starting after 9: there are 5 steps forward. (1 mark)
   2. Starting at 9 and going 5 forward shows the sum 9 + 5 = 14. (1 mark)
   3. The last jump stops on 14, which is the answer to the sum. (1 mark)
   4. Put your finger on 14 and jump back 5 times: 13, 12, 11, 10, 9. So 14 − 5 = 9. (1 mark for a correct line and 9)

5. Answer to Question 5 (4 marks)

   1. Amir takes sweets out, so subtract: 16 − 7. Take 6 to reach 10, then 1 more: 9 sweets. (1 mark)
   2. His sister adds 5, so add: 9 + 5. Make 10 with 1, then add 4: 14 sweets. (1 mark)
   3. The two number sentences are 16 − 7 = 9 and 9 + 5 = 14. (1 mark for both sentences)
   4. Fewer. The jar ends with 14 and started with 16. 14 is less than 16, and 16 − 14 = 2, so there are 2 fewer sweets than at the start. (1 mark)

Total : 20 marks