Addition Subtraction Mental Math Strategies created by Gr5AH

What is the most effective method for solving this problem: 28+ 99

• partitioning

• bridging

• re-ordering

• compensating

• doubles or doubles +/-1

28 + 99 =

• 129

• 117

• 127

• 119

What is the most effective method for solving this problem: 73 + 32

• partitioning

• bridging

• re-ordering

• compensating

• doubles or doubles +/-1

73 + 32

• 105

• 51

• 103

• 95

What is the most effective method for solving this problem: 32 + 90 + 10 + 8

• partitioning

• bridging

• re-ordering

• compensating

• doubles or doubles +/-1

32 + 90 + 8 + 10

• 150

• 120

• 130

• 140

What is the most effective method for solving this problem: 1.6 + 1.7

• partitioning

• bridging

• re-ordering

• compensating

• doubles or doubles +/-1

1.6 + 1.7

• 2.13

• 33

• 3.3

• 3.2

What are the most effective methods for solving this problem: 5.6 + 1.8

• partitioning

• bridging

• re-ordering

• compensating

• doubles or doubles +/-1

5.6 + 1.8

• 6.14

• 7.4

• 74

• 57.8