Regrouping When Multiplying

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When multiplying, you may have to regroup depending on the problem at hand. Learn about regrouping when multiplying with help from an experienced math tutor in this free video clip.

Part of the Video Series: High School Math Help
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Video Transcript

Hi, my name is Marija, I'm a mathematician. And today, I'm going to show you how to do regrouping when multiplying. So, we're going to take a two digit number like, 67 and we're going to multiply it by another two digit number like, 26. Alright, so, I'm going to start by going with this six and multiplying it by seven. So, six times seven is 42. What you're going to do is, when it is not a single digit number, that you get as a result of multiplication. Six times seven is 42. You're going to put your last digit down here, and you're going to carry the four up top, on top of the six. So, six times seven is 42, and what I did was, I regrouped it by putting the two over here. The number in the one's digit here, and the number in the ten's digit, up here. And now, you're going to multiply diagonally, six times six, is 36. And now, you have to add 36 with that four, and you get 40. So, that 40 comes on down. Now, when you're done multiplying with the six, always cross out whatever you regroup. So, you don't make the mistake of using it again in your next line. And now, multiply two digits, we're going to have to start the second line with a zero, automatically. And now, I'm going to go ahead and multiply the second number, so I have two times seven, is 14. Again, I have to regroup, because it's more than one digit. So, the fourteen is going to look like this, the four comes down here, and the one goes up, on top of the six. So, two times seven was 14, I regrouped it by putting the four down here, because it's in the one's place. And the one up here, because it's in the ten's place. And now, I'm going to multiply two times six is 12, plus one, is 13. And that 13 comes down here. And now, I'm done multiplying, so I'm going to go ahead and finish off, just by adding these two together. Two, four, seven, one,which makes my final answer, one thousand seven hundred and forty two. My name's Marija, and I just showed you how to regroup when multiplying.


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