Across the Zeros

Counting up shines exactly where borrowing hurts most: subtracting from a number full of zeros. Try 600 - 247. Borrowing would cascade through both zeros. Instead, count up: 247 plus 3 makes 250, plus 50 makes 300, plus 300 makes 600. Total: 353.

Quick guide: count up when the numbers are close or sit just under a round number, and round-and-adjust when one number is near a multiple of ten.