Step-by-step Maths Level 2 Adding within 20: check-up and practice test questions

Method. Adding zero means we add nothing. The number stays the same.

1. Look at the number. It is the number we start with.
   4
2. Add zero. Zero adds no more things.
   0 + 4 = 4
3. Write the answer. The number does not change.
   4

Check. Take zero away from 4: it is still 4.

Watch out. Adding zero never changes a number, whether zero is first or second.

Method. Split the 2-digit number into 10 and the ones. Add the ones, then add 10.

1. Split 10 into 10 and 0. The tens part is 10. The ones part is what is left.
   10 = 10 + 0
2. Add the ones: 0 + 9. Add the ones part to the number that is added.
   0 + 9 = 9
3. Add 10 back. Put the 10 back on the total.
   10 + 9 = 19
4. Write the answer.
   19

Check. Count on 9 from 10: you reach 19.

Watch out. Remember the 10 when you add the ones. 14 + 5 is 19, not 9.

Method. Adding zero means we add nothing. The number stays the same.

1. Look at the number. It is the number we start with.
   15
2. Add zero. Zero adds no more things.
   15 + 0 = 15
3. Write the answer. The number does not change.
   15

Check. Take zero away from 15: it is still 15.

Watch out. Adding zero never changes a number, whether zero is first or second.

Method. Use the number that makes 10 with the first number. Then add what is left.

1. Find what 6 needs to make 10. 6 needs 4 more to make 10.
   10 - 6 = 4
2. Split 6 into 4 and 2. Use 4 to make 10. Then add 2.
   6 = 4 + 2
3. Add the rest to 10. 6 + 4 = 10, and 10 + 2 = 12.
   10 + 2 = 12
4. Write the answer.
   12

Check. Count on: 6 + 6 = 12.

Watch out. Making 10 first is easier because 10 is simple to add to.

Method. Split the 2-digit number into 10 and the ones. Add the ones, then add 10.

1. Split 13 into 10 and 3. The tens part is 10. The ones part is what is left.
   13 = 10 + 3
2. Add the ones: 3 + 3. Add the ones part to the number that is added.
   3 + 3 = 6
3. Add 10 back. Put the 10 back on the total.
   10 + 6 = 16
4. Write the answer.
   16

Check. Count on 3 from 13: you reach 16.

Watch out. Remember the 10 when you add the ones. 14 + 5 is 19, not 9.

Method. Adding zero means we add nothing. The number stays the same.

1. Look at the number. It is the number we start with.
   5
2. Add zero. Zero adds no more things.
   5 + 0 = 5
3. Write the answer. The number does not change.
   5

Check. Take zero away from 5: it is still 5.

Watch out. Adding zero never changes a number, whether zero is first or second.

Method. Use the number that makes 10 with the first number. Then add what is left.

1. Find what 3 needs to make 10. 3 needs 7 more to make 10.
   10 - 3 = 7
2. Split 9 into 7 and 2. Use 7 to make 10. Then add 2.
   9 = 7 + 2
3. Add the rest to 10. 3 + 7 = 10, and 10 + 2 = 12.
   10 + 2 = 12
4. Write the answer.
   12

Check. Count on: 3 + 9 = 12.

Watch out. Making 10 first is easier because 10 is simple to add to.

Method. Split the 2-digit number into 10 and the ones. Add the ones, then add 10.

1. Split 12 into 10 and 2. The tens part is 10. The ones part is what is left.
   12 = 10 + 2
2. Add the ones: 2 + 5. Add the ones part to the number that is added.
   2 + 5 = 7
3. Add 10 back. Put the 10 back on the total.
   10 + 7 = 17
4. Write the answer.
   17

Check. Count on 5 from 12: you reach 17.

Watch out. Remember the 10 when you add the ones. 14 + 5 is 19, not 9.

Method. Start with the bigger number and count on the smaller number.

1. Start at the bigger number, 7. It is quicker to count on from the bigger number.
   7
2. Count on 6 more. Say 6 numbers after 7.
   7 + 6 = 13
3. Write the answer. This is the last number we said.
   13

Check. Start at 6 and count on 7. You also reach 13.

Watch out. Count on from the bigger number. Do not start again at one.

Method. Adding zero means we add nothing. The number stays the same.

1. Look at the number. It is the number we start with.
   13
2. Add zero. Zero adds no more things.
   13 + 0 = 13
3. Write the answer. The number does not change.
   13

Check. Take zero away from 13: it is still 13.

Watch out. Adding zero never changes a number, whether zero is first or second.

Method. Adding zero means we add nothing. The number stays the same.

1. Look at the number. It is the number we start with.
   7
2. Add zero. Zero adds no more things.
   7 + 0 = 7
3. Write the answer. The number does not change.
   7

Check. Take zero away from 7: it is still 7.

Watch out. Adding zero never changes a number, whether zero is first or second.

Method. Write the two parts with a plus sign, then the answer after an equals sign.

1. Write the parts. Put a plus sign between the two parts.
   12 + 6
2. Work out the total. The total goes after the equals sign.
   12 + 6 = 18
3. Write the number sentence.
   12 + 6 = 18

Check. 18 - 6 = 12. The sentence is right.

Watch out. The equals sign is for the total. Do not write the answer before the sign.

Method. Start with the bigger number and count on the smaller number.

1. Start at the bigger number, 5. It is quicker to count on from the bigger number.
   5
2. Count on 1 more. Say 1 numbers after 5.
   5 + 1 = 6
3. Write the answer. This is the last number we said.
   6

Check. Start at 1 and count on 5. You also reach 6.

Watch out. Count on from the bigger number. Do not start again at one.

Method. Start with the bigger number and count on the smaller number.

1. Start at the bigger number, 2. It is quicker to count on from the bigger number.
   2
2. Count on 2 more. Say 2 numbers after 2.
   2 + 2 = 4
3. Write the answer. This is the last number we said.
   4

Check. Start at 2 and count on 2. You also reach 4.

Watch out. Count on from the bigger number. Do not start again at one.

Method. Write the two parts with a plus sign, then the answer after an equals sign.

1. Write the parts. Put a plus sign between the two parts.
   1 + 5
2. Work out the total. The total goes after the equals sign.
   1 + 5 = 6
3. Write the number sentence.
   1 + 5 = 6

Check. 6 - 5 = 1. The sentence is right.

Watch out. The equals sign is for the total. Do not write the answer before the sign.

Method. Split the 2-digit number into 10 and the ones. Add the ones, then add 10.

1. Split 12 into 10 and 2. The tens part is 10. The ones part is what is left.
   12 = 10 + 2
2. Add the ones: 2 + 8. Add the ones part to the number that is added.
   2 + 8 = 10
3. Add 10 back. Put the 10 back on the total.
   10 + 10 = 20
4. Write the answer.
   20

Check. Count on 8 from 12: you reach 20.

Watch out. Remember the 10 when you add the ones. 14 + 5 is 19, not 9.

Method. Split the 2-digit number into 10 and the ones. Add the ones, then add 10.

1. Split 14 into 10 and 4. The tens part is 10. The ones part is what is left.
   14 = 10 + 4
2. Add the ones: 4 + 6. Add the ones part to the number that is added.
   4 + 6 = 10
3. Add 10 back. Put the 10 back on the total.
   10 + 10 = 20
4. Write the answer.
   20

Check. Count on 6 from 14: you reach 20.

Watch out. Remember the 10 when you add the ones. 14 + 5 is 19, not 9.

Method. Find the missing part. Ask what goes with the known part to make the total.

1. Start with 5. It is the part we know.
   5
2. Count on to 9. Or take the known part away from the total.
   9 - 5 = 4
3. Write the missing number.
   4

Check. 5 + 4 = 9. It works.

Watch out. Take the known part away from the total to find the missing one.

Method. Use the number that makes 10 with the first number. Then add what is left.

1. Find what 7 needs to make 10. 7 needs 3 more to make 10.
   10 - 7 = 3
2. Split 7 into 3 and 4. Use 3 to make 10. Then add 4.
   7 = 3 + 4
3. Add the rest to 10. 7 + 3 = 10, and 10 + 4 = 14.
   10 + 4 = 14
4. Write the answer.
   14

Check. Count on: 7 + 7 = 14.

Watch out. Making 10 first is easier because 10 is simple to add to.

Method. Split the 2-digit number into 10 and the ones. Add the ones, then add 10.

1. Split 19 into 10 and 9. The tens part is 10. The ones part is what is left.
   19 = 10 + 9
2. Add the ones: 9 + 1. Add the ones part to the number that is added.
   9 + 1 = 10
3. Add 10 back. Put the 10 back on the total.
   10 + 10 = 20
4. Write the answer.
   20

Check. Count on 1 from 19: you reach 20.

Watch out. Remember the 10 when you add the ones. 14 + 5 is 19, not 9.