You can use a number line to represent integer subtraction by starting at the first number (minuend) and then moving left (for subtracting a positive number) or right (for subtracting a negative number) by the amount of the second number (subtrahend).
Here's a breakdown:
- Start: Begin at the point on the number line that corresponds to the first integer (the number you're subtracting from).
- Direction:
- If you are subtracting a positive integer, move to the left (towards the negative numbers) on the number line.
- If you are subtracting a negative integer, move to the right (towards the positive numbers) on the number line. Subtracting a negative is the same as adding a positive.
- Distance: Move the number of units equal to the absolute value of the second integer (the number you're subtracting).
- End: The point where you end up on the number line is the result of the subtraction.
Examples:
- 5 - 3: Start at 5. Subtracting a positive 3 means moving 3 units to the left. You end up at 2. Therefore, 5 - 3 = 2.
- 2 - (-4): Start at 2. Subtracting a negative 4 means moving 4 units to the right. You end up at 6. Therefore, 2 - (-4) = 6.
- -1 - 2: Start at -1. Subtracting a positive 2 means moving 2 units to the left. You end up at -3. Therefore, -1 - 2 = -3.
- -3 - (-5): Start at -3. Subtracting a negative 5 means moving 5 units to the right. You end up at 2. Therefore, -3 - (-5) = 2.
Using a number line provides a visual and intuitive way to understand the concept of integer subtraction, especially when dealing with negative numbers. It helps to solidify the idea that subtracting a negative number is equivalent to adding its positive counterpart.
