Subtraction on a number line is modelled using the counting logic, visually representing the process of taking away a certain quantity from an initial value.
Here's a breakdown of how it works:
- Starting Point: Begin at the number you are subtracting from (the minuend) on the number line.
- Direction: Since you are subtracting, move towards the left on the number line. This represents decreasing the initial value. The reference material clearly states that "to subtract a positive number, we move towards the left-hand side of the number line."
- Magnitude: The number you are subtracting (the subtrahend) determines how many units you move. Each unit represents one whole number.
- Result: The number you land on after moving the specified number of units to the left is the answer (the difference).
Example:
Let's model 6 - 2 on a number line, as suggested in the reference.
- Start: Locate 6 on the number line.
- Direction: Since we're subtracting, we'll be moving to the left.
- Magnitude: We're subtracting 2, so we move 2 units to the left.
- Result: We land on 4.
Therefore, 6 - 2 = 4.
We can illustrate this in a table:
| Step | Action |
|---|---|
| 1. Start | Locate 6 on the number line. |
| 2. Direction | Move left (because we are subtracting). |
| 3. Magnitude | Move 2 units. |
| 4. Final Value | Land on 4. |
