Divide Symbol In Numbers 3.x looks like a plus
In Numbers 3.x the divide operator you enter is a forward slash "/". Numbers, however, changes the symbol to an obelus ("÷").
a zoom of the symbol looks like this:
÷
In Number when you enter the symbol you may see something like :
zoomed in it looks like this:
In some cases, it may look like the addition operator "+" and be confusing. The obelus will perform division as you expect.