How do you know if something is factorable?

Find out if a polynomial is factorable or to plug it into your calculator, and find your zeroes. If those zeroes are long decimals (or don't exist), then you probs can't factor it. Then, you'll have to use the quadratic formula. If you don't have a calc, then I don't know of any definite way in which you can tell if a polynomial is factorable or nah ...