First I show with a visual model what REGROUPING actually means in itself (before we get into subtracting). One TEN is "broken down" into TEN ONES. We practice that concept with an example, changing 7 tens 6 ones into 6 tens 16 ones (the regrouping process).
Then I also involve subtraction. We regroup (aka borrow), then subtract 2-digit numbers. Before showing the regular way this is written down (with one number under the other), I use a model based on place value for a few exercises. For example:
7 tens 0 ones is regrouped as 6 tens 10 ones.
Then we subtract:
6 tens 10 ones - 4 tens 8 ones ---------------------------- 2 tens 2 ones
Lastly we get into the regular way of writing the subtraction, such as:
62 - 27 -------
If you cannot see the video above, click here for an alternative video player.
This second video lesson provides more practice and examples of regrouping (borrowing) in subtraction, with 2-digit numbers. I also show and emphasize the importance of checking your answer by ADDING.
If you cannot see the video above, click here for an alternative video player.
Mental addition of two-digit numbers
Math Mammoth Grade 2 curriculum
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