...Subtraction is reverse skip-counting, except we skip to the left. 3 - 2 starts at 3 and skips 2 to the left to give 1. Multiplication is repeated addition: 3x2 is 3 + 3 = 6. 3 x 3 is 3 3's added together, 3 + 3 + 3 = (3 + 3) + 3 = 6 + 3 = 6, skip 3 to the right = 9. Division is reverse multiplication: if a pie is worth $10, how much would you pay for 1/4 of it. (read more)