Figuring out a number that satisfies a certain formula

I've done this before in excel, but I don't remember what it is called, but it works something like this.

Let's say you are trying to figure out the lowest integer (other than 1) that will divide into another integer without a remainder.

For example, the lowest integer that will divide into a 9 without a remainder is a 3.

So, let's say I'm trying to do this in excel. I have three cells.

cell_A = the number I am dividing into. In the above example this number would be a 9.

cell_B = the number I am trying to figure out. In the above example, this number is 3.

cell_C = cell_A / cell_B, such that the result of this formula does not give a remainder... mod(cell_A / cell_B) = 0.

How do I formulate cell_B so that cell_C meets the above condition.

I tried those two formulas... didn't work, perhaps because I mis-typed something or whatever... but these are not what I had in mind because they are both trying to solve for the number with some sort of a direct formula based on A1.

What I have in mind is something like a solver that will solve for B1 based on a certain condition on C1 which is mod(A1,B1) has to be 0.

I remember doing something like this a while ago but can't recall exactly what I did.