Subtract double-digit numbers using the same place value strategies as when adding. Shift 10, use the Make 10s subtraction strategy, and subtract multiples of 10.
Use the Make 10 Strategy to subtract a single-digit number. What's 13-5? Visualize 13 on ten frames. Subtract 5 in 2 parts. Imagine crossing off 3 to make 10, then crossing off 2 more. How many are left? 8. Check for accuracy by using or drawing counters. Since 13-3 = 10 and 10-2 = 8, 13-5 = 8. Prerequisites: 1-42, 1-41 ○ 1-37, K-109
Transition from using concrete Base 10 Discs to using pictorial number bonds. What's 86? It's 80 and 6. Shift 10. The new number bond is 70 and 16. The Funny Number "seventy-sixteen" equals the real number "eighty-six." Start by shifting 10 in 2 steps. With practice, visualize and shift 10 in 1 step. Prerequisites: 1-102
Add 2-digit and 1-digit numbers with no regrouping. First add the ones, then add back the tens to get the total. What's 26+2? Since 6+2 = 8 and 20+8 = 28, 26+2 = 28. Start by modeling numbers with concrete Base 10 Blocks or snap cubes. Progress to using pictorial number bonds and finally, just mental math. Prerequisites: 1-49
