Regrouping
Rounding to the nearest 10
Rounding and Estimating
Adding 3 Addends
Strategies
100
17+14
31
100
45
50
100
23+45
20+50=80
100
32+43+18
93
100
A strategy that can be done quickly in your head. You do not have to write it down to solve it.
Mental math question
200
47+25
72
200
32
30
200
45+16
50+20=70
200
17+43+26
86
200
Questions you have to write down. Maybe you have to write it vertically to regroup. What kinds of questions are these?
Paper and pencil
300
43+8
51
300
67
70
300
36+18
40+20=60
300
36+24+39
99
300
40+36 is what kind of problem?
Mental math
400
74+16
90
400
17
20
400
46+24
50+20=70
400
45+25+14
74
400
56+78 is what kind of problem
paper and pencil
500
16+28
60
500
25
30
500
27+21
30+20=50
500
14+30+24
68
500
What is the strategy called when we pick two choices and then check to see if the choices are right?
Guess and Check
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