Let's solve each subtraction problem using the
number line method. The idea is to start at the first number and move left (for subtraction) by the amount of the second number.
---
1) 7 - 3 = ?
- Start at
7 on the number line.
- Subtract 3 means move
3 units to the left.
- From 7 → 6 → 5 → 4
-
Answer: 4
✔ 7 - 3 = 4
---
2) -9 - (-9) = ?
- Start at
-9.
- Subtracting a negative is the same as
adding.
So, $-9 - (-9) = -9 + 9$
- Move
9 units to the right from -9.
- From -9 → -8 → -7 → ... → 0
-
Answer: 0
✔ -9 - (-9) = 0
---
3) 4 - 6 = ?
- Start at
4.
- Subtract 6 means move
6 units to the left.
- From 4 → 3 → 2 → 1 → 0 → -1 → -2
-
Answer: -2
✔ 4 - 6 = -2
---
4) -2 - 5 = ?
- Start at
-2.
- Subtract 5 means move
5 units to the left.
- From -2 → -3 → -4 → -5 → -6 → -7
-
Answer: -7
✔ -2 - 5 = -7
---
5) 1 - (-8) = ?
- Start at
1.
- Subtracting a negative is adding: $1 - (-8) = 1 + 8$
- Move
8 units to the right from 1.
- From 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → 9
-
Answer: 9
✔ 1 - (-8) = 9
---
✔ Final Answers:
1)
4
2)
0
3)
-2
4)
-7
5)
9
These answers can be verified by plotting the movements on the number lines provided in the image. Each step involves moving left for subtraction and right for addition (especially when subtracting a negative).
Parent Tip: Review the logic above to help your child master the concept of subtraction using a number line worksheet.
