Understanding subtraction part 2: multi-digit subtractionMay 8, 2020
I posted a little while ago about the importance of representations in subtraction. Today, I’m sharing a followup video on how to extend that understanding of fractions to the multi-digit case.
When you work in base 10, the algorithms and even the numbers themselves conceal information. (That’s part of what makes them powerful, paradoxically.) But if we start from understanding, we can see why the algorithms work, and extend them into diverse situations.
This video explain how to understand multi-digit subtraction as multiple simple subtraction problems, and how calling altering our representations of numbers makes the subtraction easy to do. It ends by connecting all of this to the algorithm, so that you can see why the algorithm works, and how it makes sense.