Step-by-step Maths Level 1: One bond, two kinds of sum
Part of the Step-by-step Maths Level 1 adding and taking away within 10 chapter. Chapter overview · whole chapter on one page
One bond, two kinds of sum
One number bond gives you two addition facts and two subtraction facts.
Look at the bond. The whole is at the top. Add the two parts to make the whole. Take a part away from the whole to get the other part.
Key ideas
- A bond has two parts and a whole.
- Adding the parts makes the whole.
- Taking a part away from the whole gives the other part.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 9 and one part is 4.9 and 4
- Take the part away. What is left is the other part.9 - 4 = 5
- Write the answer. 5
Check. Add back: 5 + 4 = 9. It works.
Watch out. The bond gives you a subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.7
- Count on 2 more. We add 2 to 7.7 + 2
- Write the answer. 9
Check. Count on from the other number too. You get 9 both ways.
Watch out. Count on, do not start again from one.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.7
- Take away 3. Cross out or count back this many.7 - 3
- Write the answer. This is how many are left.4
Check. Add back: 4 + 3 = 7. The answer is right.
Watch out. Count back from the first number, not up from the second.
Watch out
Watch out. Take away the part you know from the whole, not the other way round.
Exam tip
Grown-up tip. Draw a bond with two cups and one big cup. Put counters in the small cups, then ask your child to find the total and the missing part.
Exercise 8A One bond, two kinds of sum
Non-calculatorMethod. Take the part you know away from the whole.
- Read the bond. The whole is 8 and one part is 6.8 and 6
- Take the part away. What is left is the other part.8 - 6 = 2
- Write the answer. 2
Check. Add back: 2 + 6 = 8. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.4
- Count on 3 more. We add 3 to 4.4 + 3
- Write the answer. 7
Check. Count on from the other number too. You get 7 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 9 and one part is 8.9 and 8
- Take the part away. What is left is the other part.9 - 8 = 1
- Write the answer. 1
Check. Add back: 1 + 8 = 9. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.3
- Count on 3 more. We add 3 to 3.3 + 3
- Write the answer. 6
Check. Count on from the other number too. You get 6 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 5 and one part is 4.5 and 4
- Take the part away. What is left is the other part.5 - 4 = 1
- Write the answer. 1
Check. Add back: 1 + 4 = 5. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.5
- Count on 3 more. We add 3 to 5.5 + 3
- Write the answer. 8
Check. Count on from the other number too. You get 8 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 10 and one part is 1.10 and 1
- Take the part away. What is left is the other part.10 - 1 = 9
- Write the answer. 9
Check. Add back: 9 + 1 = 10. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.6
- Count on 4 more. We add 4 to 6.6 + 4
- Write the answer. 10
Check. Count on from the other number too. You get 10 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 7 and one part is 3.7 and 3
- Take the part away. What is left is the other part.7 - 3 = 4
- Write the answer. 4
Check. Add back: 4 + 3 = 7. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.7
- Count on 3 more. We add 3 to 7.7 + 3
- Write the answer. 10
Check. Count on from the other number too. You get 10 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 8 and one part is 7.8 and 7
- Take the part away. What is left is the other part.8 - 7 = 1
- Write the answer. 1
Check. Add back: 1 + 7 = 8. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.8
- Count on 2 more. We add 2 to 8.8 + 2
- Write the answer. 10
Check. Count on from the other number too. You get 10 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 3 and one part is 2.3 and 2
- Take the part away. What is left is the other part.3 - 2 = 1
- Write the answer. 1
Check. Add back: 1 + 2 = 3. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.8
- Count on 1 more. We add 1 to 8.8 + 1
- Write the answer. 9
Check. Count on from the other number too. You get 9 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 10 and one part is 2.10 and 2
- Take the part away. What is left is the other part.10 - 2 = 8
- Write the answer. 8
Check. Add back: 8 + 2 = 10. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.9
- Count on 1 more. We add 1 to 9.9 + 1
- Write the answer. 10
Check. Count on from the other number too. You get 10 both ways.
Watch out. Count on, do not start again from one.