Adding and Subtracting 3-Digit Numbers
Learning Objective
I can add and subtract three-digit numbers using the standard algorithm, showing regrouping when needed.
Key Concepts
When rewriting a multi-digit subtraction problem, the number you are taking from goes on top, and the number you are taking away goes on the bottom.
When subtracting, always start with the ones place column, and if the top digit is smaller than the bottom digit, you need to borrow.
If you need to borrow from a digit that is zero, you have to borrow from the next two digits instead of just one.
Practice Questions
This lesson includes 3 practice questions to reinforce learning.
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1. When subtracting multi-digit numbers, which number goes on top when rewriting the problem?
2. Explain the process of borrowing (regrouping) in subtraction. Why is it sometimes necessary, and what does it involve?
3. Solve the following subtraction problem, showing your work and explaining any regrouping: 406 - 28
Educational Video
Math Antics - Multi-Digit Subtraction
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