Simple Subtraction: Help for Struggling Students

Subtraction for Struggling Students

Subtraction is the opposite of adding. When you add, you begin with a certain number, and you increase this amount by another number. When you subtract, your starting number becomes smaller. Below are several activities to help you make sense of subtraction.

Make a Number Line

You can use a ruler as your number line. Alternatively, if you don't have a ruler, you can just draw a line on a piece of paper. Start with zero, and then make 12 evenly spaced marks to the right. Label them with the numbers 1-12. If you need to solve subtraction problems with higher numbers, you'll need to make your number line longer. Here's how you can use this number line to solve subtraction problems:

1. When you're subtracting, the order of the numbers is critical. You must always subtract from left to right. Find the number on the left side of your subtraction problem on the number line. For instance, if your problem is 11 - 3, find the number 11. Sometimes, subtraction problems are written vertically. In this case, you'll want to find the top number.

2. The next number in your subtraction problem tells you to move a certain number of spaces to the left on your number line. In this problem, the second number is three, so you'll count three spaces to the left of 11.

3. The number you land at is the correct answer. Since eight is three spaces to the left of 11, the answer is 11 - 3 = 8.

Use Objects

Instead of a number line, you can also use small objects to visualize subtraction problems. Start with a handful of buttons, coins or candies. To solve a problem like 15 - 12, begin by counting out 15 objects. Then, take away 12 of them. The number of objects remaining is the answer to your problem (15 - 12 = 3).

Learn Place Values

Understanding place values can help you work with larger numbers. A 2-digit number has two places: the ones place and the tens place. In the number 23, the three is in the ones place (23), and the two is in the tens place (23). This tells you that 23 is equal to three ones and two tens, so 1 + 1 + 1 + 10 + 10 = 23.

You can use place values to help you subtract by tens. For example, the problem 56 - 10 might seem daunting at first, but all you need to do is subtract one from the tens place: 56 - 10 = 46. If you're asked to solve 56 - 20, you'll just subtract two from the tens place: 56 - 20 = 36.