How to Divide With 2 Digits


How to divide with two digits. I'm Bon Crowder and we're talking about specifically dividing by two digit numbers. So here we have a four digit number divided by a two digit number. This is going to provide us adequate play room for these kind of things. So 28 into 7489, we start just like we normally would with old fashioned long division and as grownups we might look at and go 28 goes into 74 so many times if you just know it. But, if we're not so familiar with that or if we are younger, we might not be able to see how many times 28 goes into 74 so what we do is we cover up these second spots and we only look at the 2 and the 7. We go how many times does 2 go into 7? Well 2 goes into 7, 3 times. So we're going to start with 3. I'm going to say 28 goes into 74, 3 times, that's my guess. Then I multiply, 3 x 8 so I can go over here and do this, 28 x 3, 3 x 8 is 24, 3 x 2 is 6, 7, 8, 84, oh no, if I put 84 here and subtract, you get a negative. Okay, so 3 is totally not going to work. So this is where our handy little checklist here comes in. So I learned this in the third grade or something is drive my super cool buggy so it means divide, multiply, subtract, compare, bring down. This compare is what we're doing. So, 84 is bigger than 74 so when I, well actually we're doing the subtract and it doesn't work right? And then we're going to compare, 74 - 84 doesn't work so I need to go down a little bit, so I'll erase that guy and erase this guy. I had a 3 there so I'm going to go down 1 to 2, 28 x 2 is 1656. So now I'm going to subtract, 6 and 8 is 14, 5, 6, 18, here's the compare, is 18 bigger than 28, no, 18 is smaller than 28 so we're good. We were able to subtract and then we didn't have a bigger number here. Now we're ready to bring down, okay, here we go again. How many times does 28 go into 188? Who knows that kind of thing? So, we cover up the last digit and we go how many times does 2 go into 18, well 2 goes into 18 9 times. So we go okay, we're going to try 9, it may not work but it may. It's a good starting place. So we do 28 x 9, 9 x 8 is 72, 9 x 2 is 18 + 7 is 25, oh my heavenly days. If I put 252 here and try to subtract it, that is crazy talk. This subtraction doesn't work, my 9 is way too big. So I go okay, get rid of the 9, I've got to go down some, 252 is really big so now I can either guess and go 8, 7, 6, maybe a 5, let's try that. So 28 x 5, 8 x 5 is 40, 5 x 2, 140, we can definitely subtract now, 8 take away 0, 8 take away 4, that's a 0, subtraction worked, compare, man 28 goes into 48 another time. So this 5 was still wrong. Alright, so let's take the 5 and go up to 6, keep your fingers crossed, right, 28 x 6, 6 x 8, 48, 6 x 2 is 12 plus 4 is 16, subtracting, compare is 20 less than 28, yes, finally, holy cow. Now we're ready to bring down the 9, oh my goodness, again, cover up that last digit. How many times does 2 go into 20, 10, can't put a 10 there, we can go 9 but our experience is is we keep overshooting it, so let's maybe go 8. So 28 x 8, 8 x 8 is 64, 8 x 2 is 16 + 6 is 224, oh, bust. How about 28 x 7, 7 x 8 is 56, 7 x 2 is 14, 196, ooh, look 196 would work. So I can put a 7 there, multiply 196, subtract and I have a remainder of 13. So, division with 2 digit numbers kind of takes a little bit of trial and error. I'm Bon Crowder, enjoy it.

Bon Crowder has taught math to over 15,000 adults in living rooms, classrooms and conferences.