Number Line Subtraction
A number line makes subtraction visible. Subtracting means moving left — the opposite direction to addition.
Take-Away on a Number Line
Start at the minuend and jump left by the size of the subtrahend.
10 − 4: start at 10, jump left 4 → land on 6
Counting Up to Find the Difference
Start at the subtrahend and count up to the minuend. The number of steps is the difference.
13 − 8: start at 8, count up to 13 → 5 steps → difference = 5
Bridging Through Ten
23 − 8: jump left 3 to reach 20, then left 5 more → land on 15
Large-Jump Method
67 − 34: jump left 30 → 37; jump left 4 → 33
Which Method?
| Method | Best for | Direction |
|---|---|---|
| Jump left | Small subtrahends, visual learners | Left |
| Count up | Numbers close together | Right |
Key Takeaways
- Subtraction on a number line = jumping left.
- Counting up from subtrahend to minuend gives the same answer more efficiently when numbers are close.
- Bridging through ten is powerful when a subtraction crosses a multiple of 10.
Practice Questions
- Use a number line to show 14 − 6.
- Use counting up to find 20 − 13.
- Use bridging to find 31 − 7.
- Use the large-jump method for 85 − 42.
- Why is counting up better for 200 − 195?