Add to 100 - Shift 10 3-3
Use number bonds and a partial sums strategy to add 2-digit numbers with regrouping. What's 36+15? Since 30+10 = 40, 6+5 = 11, and 40+11 = 51, 36+15 = 51. Find and add partial sums to get the total sum. Progress from number bonds to equations. With practice, use mental math to become fluent within 100.
