Algorithm 1
55+12
67
10+51
61
Estimate the sum for 58 + 23
58 --> 60
23 --> +20
80
Solve using the partial sums strategy: 56+32
50 + 6
+ 30 + 2
80 + 8 = 88Solve using the base ten block strategy: 31 + 42
Teacher will check answer
38+38
76
68+26
94
Estimate the sum 27 + 58
27 --> 30
58 --> +60
90
Solve using the partial sums strategy: 62 + 24 =
60 + 2
+ 20 + 4
80 + 6 = 86
Solve using the partial sums strategy: 74 + 14 =
70 + 4
+ 10 + 4
80 + 4 = 88
16+14
30
15+36
51
Estimate the sum for 40 + 36
40 --> 40
36 --> +40
80
Solve using the partial sums strategy: 68 + 26
60 + 8
+ 20 + 6
80 + 14 = 94
Solve using the algorithm strategy: 68 + 29
97
54 + 38
92
58+29
87
Estimate the sum for 78 + 15
78 --> 80
15 --> +20
100
Solve using the partial sums strategy: 53 + 29 =
50 + 3
+ 20 + 9
70 + 12 = 82
Estimate the sum for 67 + 27
67 --> 70
27 --> +30
100