Current time:0:00Total duration:2:49
0 energy points
Ready to check your understanding?Practice this concept
Sal divides 7182÷42.  There is no remainder. Created by Sal Khan.
Video transcript
Let's divide 7182 by 42. Now what's different here is we're now dividing by two-digit number, not a one-digit number. But the same idea holds. So we say: "Hey, how many times does 42 go into 7?" Well, it doesn't really go into 7 at all so let's add one more place value. How many times does 42 go into 71? Well it goes into 71 one time and we're really... Just the reminder of what happens during the process: You're saying: "Hey 42 goes into 71 one time.", but we're really saying: "42 goes into 7100 one hundred times", because we're putting this one in the hundreds place. But let's put that on the side for a little bit and focus on the process. So 1 times 42 is 42 and now we subtract: Now, you might be able to do 71 minus 42 in your head knowing: "Hey, 72 minus 42 would be 30 so 71 minus 42 would be 29." But we could also do it by regrouping. To regroup you want to subtract the 2 from a 1, well that's not so you can really do that (in the traditional way) so let's take a 10 from the 70 (so that becomes a 60) and give that 10 to the ones place and then that becomes an 11. And so 11 minus 2 is 9 and 6 minus 4 is 2. So you get 29. And we can bring down the next place value. Bring down an 8. And now this is really art happens when we're dividing by multi-digit number right over here. We have to estimate how many times does 42 go into 298. And sometimes it might envolve a little bit of trial-and-errors. You really just kind of have to eyeball it, if you made a mistake, try again. The way you know you make a mistake is as if you say... it goes into 9 times, you do 9 times 42 and you're in the number larger than 298, then you overestimated. If you say it goes into it 3 times, you do 3 times 42, you get some number here, when you subtract you get something larger than 42, then you also made a mistake and you have to adjust upwards. But let's see if I can eyeball it. So this is roughly 40, this is roughly 300. 40 goes into 300 the same times as 4 goes into 30 soit's going to be roughly 7. Let's see if that's right. 7 times 2 is 14, 7 times 4 is 28, plus 1 is 29. So we've got pretty close. My remainder here: Notice 294 is less than 298 so I'm cool there and my remainder is less than 42 so I'm cool as well. So now let's add another place value. Let's bring this 2 down. And here we're just asking ourselves: "How many times does 42 go into 42?" Well, 42 goes into 42 exactly one time. 1 times 42 is 42 and we have no remainder. So this one luckily divided exactly. 42 goes into 7182 exactly 171 times.