Subtract Double-Digit Numbers with Regrouping using Number Bonds 2-35
Transition from using concrete Base 10 discs to model regrouping problems, to using pictorial number bonds. What's 64–28? 64 in expanded form is 60 and 4. 28 is 20 and 8. There are not enough ones, so shift 10. "Sixty-four" becomes "fifty-fourteen." Since 50-20 = 30, 14-8 = 6, and 30+6 = 36, 64-28 = 36.
