average result: x1 + x2 + x3.....+ xn / n is the Average http://www.chem.tamu.edu/class/fyp/mathrev/std-dev.pdf And median is the number in the middle. I've asked my friends studied Math in English, no medium, only has median in math. Response to the Wao Tao's question. BTW, a class in next few minutes, haven't check out that mail box, just send to your uow's mailb. Regards, Gary Cheers, Gary