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Current time:0:00Total duration:2:24

Worked example: Subtracting 3-digit numbers (regrouping from 0)

CCSS.Math: ,

Video transcript

let's try to subtract 164 from 301 and I encourage you to pause this video and try it on your own first so let's go place by place and we can realize where we have to do some borrowing or regrouping so the ones place we have an issue 4 is larger than 1 how do we subtract a larger number from a smaller number we also have an issue in the tens place 6 is larger than 0 how do we subtract 6 from 0 so the answer that might be jumping into your head is oh we've got to do some borrowing or some regrouping but then you might be facing another problem you would say ok well let's try to borrow from the tens place here so we have a 1 if we could borrow 10 from the tens place could be at 11 but there's nothing here in the tens place there's nothing to borrow so what do we do so the way I would tackle it is first borrow for the tens place so we have nothing here so let's regroup a hundred from the hundreds place so that's equivalent to borrowing a 1 from the hundreds place so that's now a 2 and now in the tens place instead of a 0 instead of a 0 we are going to have a 10 now let's make sure that this still makes sense this is 200 plus 10 10 10 10 is a hundred plus 1 200 plus 100 plus 1 is still 301 so this still makes sense and the reason why this is valuable is now we have something to regroup from the tens place if we take one of these tens one of these tens so now we're left with nine tens and we give it we give it to the ones place so you give 10 plus one you're going to be left with you're going to be left with 11 and we can verify that we still haven't changed the value of the actual number 200 plus 90 is 290 plus 11 is still 301 and what was neat about this is now up here all of these numbers are larger than the corresponding number in the same place so we get we're ready to subtract 11 minus 4 11 minus 4 is let's see oh let's see 10 minus 3 is 7 so 11 minus 4 is 7 9 minus 6 is three and two minus one is one so we are left with 137