245 – 137 using a number line
The Correct Answer and Explanation is:
Answer:
245 – 137 = 108
Explanation Using a Number Line
To solve 245 – 137 using a number line, we start by locating 245 on the number line. Since we are subtracting, we will move left on the number line.
Here’s how to break it down step by step:
- Start at 245.
- Subtract 100 first to simplify the process:
245 – 100 = 145
So we move 100 units to the left and land at 145. - Next, subtract 30:
145 – 30 = 115
Move 30 more units to the left and land at 115. - Finally, subtract 7:
115 – 7 = 108
Move 7 units more to the left and land at 108.
So, after subtracting 100, then 30, then 7 (a total of 137), we end at 108.
This method is called “decomposing” or “breaking apart” the number you are subtracting into manageable chunks (100 + 30 + 7) to make it easier to subtract in steps. It’s especially helpful for visual learners who understand math better with number lines or mental math strategies.
Why this works:
Using a number line helps illustrate subtraction as “taking away” or “moving backward.” Instead of doing the entire subtraction in one jump, we break it down. This mirrors how our brains often do math mentally—by simplifying the problem into easier steps. For example, subtracting 100 is a familiar and easy step. Then subtracting 30 and 7 is more manageable than jumping straight from 245 to 108.
It’s also a good way to teach place value:
- The 100 is from the hundreds place,
- The 30 from the tens place,
- The 7 from the ones place.
So, 245 – 137 = 108, and the number line shows this clearly step by step.
