I know you can look on the periodic table, but if I don't have one handy, is there an equation or something that I can use?

 

I also know that the electronegativity increases from left to right, and the farther up the periodic table you go, but I would like to find specific numbers. (to use in finding what kind of bond it is.)

No you cant. Electronegativity is not a physical property it is just used to explain things. You have too look them up

Darn it.

 

Okay, thanks.

actually you can calculate the electronegativity, but its usefulness is limited if you don't even have access to a periodic table.

 

http://en.wikipedia.org/wiki/Electronegativity

As insane_alien said one can calculate electronegativity. there are scales of electronegativity and of them all (3 i think) paulings scale is most commly used by chemists but it is just qualitative, and the numbers are supposed from a scale of 1-4. But allens, mulikkens etc have mathematical expressions with which it is possible to calculate the electronegativity and they are in good agreement to the paulings scale of electronegtivities.