Step-by-step Maths Level 2: Number sentences

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

1. Start with 6. It is the part we know.
   6
2. Count on to 10. Or take the known part away from the total.
   10 - 6 = 4
3. Write the missing number.
   4

Check. 6 + 4 = 10. It works.

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

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

1. Start with 11. It is the part we know.
   11
2. Count on to 18. Or take the known part away from the total.
   18 - 11 = 7
3. Write the missing number.
   7

Check. 11 + 7 = 18. It works.

Watch out. Take the known part away from the total to find the missing 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. Find the missing part. Ask what goes with the known part to make the total.

1. Start with 10. It is the part we know.
   10
2. Count on to 16. Or take the known part away from the total.
   16 - 10 = 6
3. Write the missing number.
   6

Check. 10 + 6 = 16. It works.

Watch out. Take the known part away from the total to find the missing 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.
   14 + 2
2. Work out the total. The total goes after the equals sign.
   14 + 2 = 16
3. Write the number sentence.
   14 + 2 = 16

Check. 16 - 2 = 14. The sentence is right.

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

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

1. Start with 13. It is the part we know.
   13
2. Count on to 19. Or take the known part away from the total.
   19 - 13 = 6
3. Write the missing number.
   6

Check. 13 + 6 = 19. It works.

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

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

1. Start with 11. It is the part we know.
   11
2. Count on to 14. Or take the known part away from the total.
   14 - 11 = 3
3. Write the missing number.
   3

Check. 11 + 3 = 14. It works.

Watch out. Take the known part away from the total to find the missing 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.
   5 + 11
2. Work out the total. The total goes after the equals sign.
   5 + 11 = 16
3. Write the number sentence.
   5 + 11 = 16

Check. 16 - 11 = 5. The sentence is right.

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

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.
   5 + 5
2. Work out the total. The total goes after the equals sign.
   5 + 5 = 10
3. Write the number sentence.
   5 + 5 = 10

Check. 10 - 5 = 5. The sentence is right.

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

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

1. Start with 13. It is the part we know.
   13
2. Count on to 15. Or take the known part away from the total.
   15 - 13 = 2
3. Write the missing number.
   2

Check. 13 + 2 = 15. It works.

Watch out. Take the known part away from the total to find the missing 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.
   8 + 12
2. Work out the total. The total goes after the equals sign.
   8 + 12 = 20
3. Write the number sentence.
   8 + 12 = 20

Check. 20 - 12 = 8. The sentence is right.

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

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

1. Start with 2. It is the part we know.
   2
2. Count on to 10. Or take the known part away from the total.
   10 - 2 = 8
3. Write the missing number.
   8

Check. 2 + 8 = 10. It works.

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

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

1. Start with 14. It is the part we know.
   14
2. Count on to 20. Or take the known part away from the total.
   20 - 14 = 6
3. Write the missing number.
   6

Check. 14 + 6 = 20. It works.

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

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

1. Start with 3. It is the part we know.
   3
2. Count on to 17. Or take the known part away from the total.
   17 - 3 = 14
3. Write the missing number.
   14

Check. 3 + 14 = 17. It works.

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

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

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

Check. 2 + 3 = 5. It works.

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

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

1. Start with 7. It is the part we know.
   7
2. Count on to 18. Or take the known part away from the total.
   18 - 7 = 11
3. Write the missing number.
   11

Check. 7 + 11 = 18. It works.

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