Then if x = its hundreds digit then x+1 = its tens digit and x+2 is its units digit So the number is 100x + 10(x+1) + (x+2) = 100x + 10x + 10 + x + 2 = 111x + 12 If you let x=1, you get it immediately, because 111(1) + 12 = 111 + 12 = 123 and 123 + 2 = 125 = 5^3 and 123 - 2 = 121 = 11^2 Edwin