# How to check algebraic long division?

1. ### Tyrion101

154
My errors all involve multiplying numbers that look the same, for instance if there is a 2 that I'm supposed to multiply by a 2a I'll put 2 a, and not think about it till I see I got the answer wrong. Is there a way I can do something to the answer to see if it is right before I submit it?

2. ### economicsnerd

263
Division is just multiplication backward. Multiplication is usually much easier and less error-prone. If I understand correctly, you're asking: "If I try to compute f/g and get answer h, how do I check whether it's correct?" If that's the question, then a quick check is to compute g*h and see whether you get f.

3. ### symbolipoint

3,345
Multiplying the individual terms requires a little bit of conscious focus. One must watch what one is doing.

Yes. Multiply the resulting quotient by the divisor. When you simplify this multiplication, to general form, it must match the dividend.

4. ### Tyrion101

154
Don't know why it didn't occur to me, but that makes sense. Thanks.