Did you once struggle with subtraction when there was a lot of borrowing involved, especially when there were multiple zeros in the first number? Maybe you now have a child who struggles with it. You're not alone!
I've worked with students who were assigned subtraction handouts with a painful number of questions to complete. This can be grueling, especially if the standard algorithm feels like a lot of steps to memorize.
I have seen many students struggle with the standard algorithm for subtraction, especially with problems like this one shown. Let's try a different way to solve this kind of problem. Why not!?
It is important for students to realize that many times, there are different ways to answer the same problem.
It's important to remember that subtraction can be thought of as the difference between two numbers. Or, if the two numbers were on a number line, it could be thought of as the distance between the two numbers. For the numbers shown above, 6,000 minus 926 can be thought of as the distance between 6,000 and 926, shown below.
If we're interested in the distance between the two numbers, if I shift each number down the number line equally (let's say by 1 each), then the distance between the two numbers wouldn't change. See below.
Since the distance hasn't changed, the answer to the subtraction problem hasn't changed. But what HAS changed is that if I write the problem using the new, red numbers, it's much easier to use the standard algorithm! There is no longer a need to borrow! See below.
We would have gotten this same answer of 5,074 if we subtracted 6,000 - 926 also. If the standard algorithm is stressful for you or your child, you can use this strategy. It's a smart way to use math to your advantage!
Here’s a video showing another example. 🤗🎉💫
Reach out with any questions you have.
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Melissa Agocs
Online Math Tutoring and Enrichment