Dividing by a 2-digits: 4781÷32

- [Instructor] In this video we're going to get a little bit of practice divided by a two digit number. So let's say that we have 4,781 divided by 32. Pause this video and see if you can figure out what that's going to be. And if there is a remainder, figure out what that remainder is going to be. All right, now let's work on this together. So first let me rewrite 4,781 and this is going to be divided by 32. Now whenever we divide by anything that has more than one digit, so it's a little bit of an art. The way we're going to tackle it is a little trial and error using estimation. So we'll start by saying "Hey, "how many times does 32 go into four?" Well, 32 doesn't go into four at all, so then we'll move on. How many times does 32 go into 47? Well it's pretty clear that 32 goes one time into 47. So I'll put the one right over there, above the seven in 47. And if you're saying, "Hey, how did Sal know that?" Well, just remember, two times 32 would be 64. That's more than 47. So 32 goes into 47 one time, and we multiply one times 32. One times two is two, one times three is three. You know that one times 32 is 32. And then we subtract 32 from 47. Let's do that, and we get seven minus two is five and four minus three is one. And the way you make sure that you did that step right is whatever we get over here should be less than 32. If whatever we have here is 32 or greater, that means we could of had a larger number up here. But then our next step is we bring down the eight and we say, "How many times does 32 go into 158?" Now this is a little bit tricky. If you were estimating how many times does 30 go into 150, you might say five. And actually this is for kicks, let's just try that out. Let's see if five works. So let's see, five times two is 10. We'll put zero ones and then we will have one 10 there, carry the one. Fives times three is 15, plus one is 16. So that didn't work out. It almost worked out, but not quite. 160 is larger 158 so five is too much there. So we need to go down to four. So four times two is eight. Four times three is 12. And now we subtract and 158 minus 128, eight mins eight is zero, five tens minus two tens is three tens, and then we have no hundreds. And then this is right, 'cause 30 is less than 32. And then we can bring down, we can bring down that one. Now how many times does 32 go into 301? Well we might be tempted to say, "Well, this is close to 30, "this is close to 300, so maybe it's 10." But 10 times 32 would be 320, so that'd be too much. So I feel good about nine as my estimate. Nine times two is 18, carry the one. Nine times three is 27, plus one is 28. And then we can subtract. We're actually going to have to do a little regrouping here. You might be able to do it in your head. To go from 288 to 301, let's see, you would add 12 to get to 300 and then one more, 13. So you might be able to do it in your head that this is going to be 13, or you could regroup. You could say, "All right, let's see, "one is less than eight, can I regroup from the 10s place? "No, I have nothing there so I have to regroup "from the hundreds place. "So I'm gonna take one of those hundreds, "I'm left with two hundreds left. "And then I'm going to have 10 10s. "And then I could take one of those 10s, "so I have nine 10s left, and give it to the ones place "so now I have 11 ones. "And 11 minus eight is 3, nine 10s minus eight 10s "is one 10, and then hundreds, "200 minus 200 is just a zero." And so there we have it, this is less than 32. We have nothing left to bring down and so we're left with the remainder of 13. So this is going to be equal to 149 with a remainder of 13, and we're done.