Grade 2 Addition and Subtraction Strategies

OPEN NUMBER LINE - ADDITION

145 + 49 = ___

145

185 190 194

+40

+5 +4

OPEN NUMBER LINE - SUBTRACTION

91 – 75 = _____

91

16 20 21

-70

-4 -1

EXPANDED FORM - ADDITION

145 100 + 40 + 5 + 49 40 + 9

100 + 80 + 14100 + 80 + 10 + 4 = 194

KEEP ONE /BREAK ONE - SUBTRACTION

91 – 75 = ____

91 – 70 = 21 (Subtract the tens) 21 – 5 = 16 (Subtract the ones)

PARTIAL SUMS - ADDITION

145 + 49 = _____

145+ 49

( add the hundreds) 100 (add the tens) 80 (add the ones) 14

194

STANDARD ALGORITHM

1 8 11145 91

+ 49 - 75194 16