How to Do Long Division

Video Transcript

"Hi, I'm Steve Jones, and I'm going to explain how to do long division. First of all, long division is usually dividing by numbers greater than twelve, because any number up to twelve you can divide in the normal way. But, a number bigger than twelve we have difficulties with, and I've selected thirteen, and to make it simple to actually do on the board and explain. My normal way of doing it will be to put the number that we're going to be dividing there, two hundred and thirty. And we're going to divide it by thirteen, so I would put the thirteen here, on this side. All right? Now, when I start this process, my decimal point is here, remember. First of all, I'll say, try and divide thirteen into two. Well, obviously, thirteen doesn't go into two, so that's simple enough, it won't. But thirteen will go into twenty three. And it means that I'm already at this point, and my first figure will go here. Thirteens, I can only get one thirteen in twenty three, right? Which gives me thirteen. Okay? So I'll put the thirteen here, that's the thirteen, okay? Now, I now have to subtract the thirteen from the twenty three. I will get one, zero, and now I bring down the next number. Now I say thirteens into one hundred. Well, thirteens into a hundred, well, there's one, two, three, four, five, six, seven thirteens will give me ninety one. And I'll put the ninety one there. Normally what I'd do is say, "Seven threes are twenty one. Seven ones are seven. Eight, nine, ninety one. All right? Now here's the decimal point, okay, so my answer at the moment is seventeen here, right? But now, a hundred minus ninety one, we know, will give me nine. I'll get nine here. So, here we have the twelve remaining. We bring down the next zero, thirteens into a hundred and twenty will be a hundred and seventeen, which is actually nine, and we'll get our hundred and seventeen here, and, of course, we get three left, and so on. And I can keep going on, but I don't have to go any further to show you that we've got a seventeen point six nine as the answer. The problem with long division is that you can keep doing it as long as you like, you will get a very, very long number here. But there is no point going to more than four significant figures, two places of decimals in this case. So this is simply how to do long division."