Another subject of great interest to the Pythagoreans was how to find the average, or mean, of two positive numbers. At first thought this seems to be a trivial question. Let the numbers be and b. Add them and divide by 2, getting (a+b)/2: you are done. Today, of course, we would compute this mean numerically; for example, the mean of 3 and 5 is (3+5)/2=8/2=4.the Greeks, however, thought of it in terms: they regarded a and b as the lengths of two line segments, drawing them end to end along one line and finding the midpoint of the combined segment-all doable with straightedge and compass(see chapter 18).