Dividing 3-digit numbers by 2-digit numbers
About this video
This video uses long division to divide 3-digit numbers by 2-digit numbers. It shows 868 ÷ 28 = 31 and 724 ÷ 53 = 13 remainder 35, estimating each digit of the quotient by rounding, then multiplying, subtracting with regrouping and bringing down the next digit.
You'll be able to
- estimate each digit of a quotient by rounding the divisor.
- carry out long division steps: multiply, subtract, bring down.
- identify the remainder and explain why it is less than the divisor.
Key words
- long division
- A step-by-step way to divide: estimate, multiply, subtract, then bring down the next digit.
- regrouping
- Taking 10 from one place to give to the place next to it so you can subtract.
- remainder
- The amount left over that is too small for the divisor to go into again.
Transcript
- [Instructor] Let's get a little bit more practice dividing. So let's say we wanna figure out what 868 divided by 28 is. Pause this video and see if you can figure that out. All right, now let's work through this together. So we're going to take 28, we're going to divide it into 868.
So the first thing I would do is try to estimate how many times would 28 go into 86? So let's see, 28 is a little bit less than 30 and 86 is a little bit less than 90. 30 would go into 90 about three times. So let me try three here. So let me put a three there and let's figure out what three times 28 is.
Three times eight is 24, and then three times two is six plus two is eight. Looks like I did that right. I just got right below it, I didn't go over it. And so here, 86 minus 84 is two. Bring down this eight right over here and lemme get rid of that so it doesn't confuse me.
How many times does 28 go into 28? Well, that one's pretty straightforward. It goes exactly one time. One times 28 is 28, and I'm done. And I'm left with no remainder. Let's look at another example here. Let's say we wanted to figure out what 724 divided by 53 is.
Pause the video and have a go at that. All right, so we have 53 and we're trying to figure out how many times does it go into 724? So first estimating how many times does 53 go into 72? Well, it goes at least once. It doesn't go twice because that'd be over 100.
So lemme just put a one here. One times 53 is 53. Now let me subtract. You might be able to do this in your head. You might say, okay, 73 minus 53 would be 20, but this is 72, so it'd be 19. But let's just do this with regrouping just to make sure we're doing it well.
So let's see. I can take a 10 from here. So that becomes a six and I give that 10 to this two. So it becomes a 12. 12 minus three is nine, six minus five is one. And now let me bring down this four. So I'm trying to figure out how many times does 53 go into 194?
So let's see, 50 would go into 200, I'm just estimating by rounding to the nearest, well, in this case, rounding to the nearest 100 but let's see. 50 goes into 200 about four times or exactly four times. This is less than 200 and this is greater than 50. So I'm gonna try three.
Three times three is nine. Three times five is 15. And now let me subtract and let's see, I can regroup again. I can take 10 from here, Put it over here. So then that becomes 14. 14 minus nine is five. Eight minus five is three. And then 100 minus 100 or one minus one is zero.
So I'm left with a remainder of 35 and that is a remainder because I can't divide 53 into it anymore. So I get this is equal to 13, remainder 35, and we're done.
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