using resistors

I don't have a resistor of the value that I need. I do have 2 that add up the the value that I need. How would I use 2 to get what I need? I could go get the correct value but I didn't want to run to the store if I didn't have too. I need 250 Ohms and all I have are a 100 Ohm and a 150 Ohm. Also, I'm looking through all my resistors to see if I have a 1500 Ohm but I don't think I do. I have several that I could pair up to get this one as well.

If you connect one end of the 100 ohm resisto to one end of the 150 ohm resistor, this will make a 250 ohm resistor.  In a series circuit, Resistor 1  plus  Resistor 2   plus  Resistor 3   equals total resistance.