Calculating distance moved from X & Y value inputs from sensors

Two sensors input X & Y values from a 2-axis table. I need to calculate the distance traveled, to use as a motor input command. The Hypotenuse is what I'm needing: sqrt( sq(X) + sq(Y)).
But there's no provision for getting the square root. Is there some other 'long hand' math that I can do this with? Am I correct that the microscript only supports abs, mod, and + - * /
There's got to be a way to come up with travel distance from the X val and Y val.1