something i do for more general two digit multiplies is to work from left to right, like he states. take his example, 27 squared: 2x2 = 4 2x7 + 2x7 (cross) = 2

something i do for more general two digit multiplies is to work from left to right, like he states. take his example, 27 squared: 2x2 = 4 2x7 + 2x7 (cross) = 28, carry the 2 now you have 68 7x7 = 49, carry the 4 729 it's usually fast enough for me, and i don't have to remember other tricks.