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3rd – 5th grade SubtractionPlace Value and Negative Numbers
Category 1“The following number talks consist of computation problems that begin the discussion of what happens when you remove a larger number from a smaller quantity. The number line will be an important tool to use when reasoning with this strategy.”
Parrish, S. (2010). Number talks: Helping children build mental math and computation strategies, grades K-5. Sausalito, CA: Math Solutions.
Example of what this strategy might look like:123 – 59 (100 + 20 + 3) – (50 – 9)100 – 0 = 10020 – 50 = -303 – 9= -6100 – 30 = 7070 – 6 = 64
Parrish, S. (2010). Number talks: Helping children build mental math and computation strategies, grades K-5. Sausalito, CA: Math Solutions.
5 – 55 – 6 5 – 75 – 8
0 – 10 – 2 0 – 30 – 5
6 – 66 – 7 6 – 86 – 9
4 – 44 – 5 4 – 64 – 7
20 – 100 - 4
20 - 14
20 – 101 - 3
21 - 13
20 – 102 - 4
22 - 14
20 – 103 - 5
23 - 15
20 – 105 - 6
25 - 16
Category 2“The following number talks consist of two-digit computation problems to continue the work with this strategy. A deliberate sequence is used to support thinking for the initial problem in each section. The last problem in each section allows students to test their thinking with a similar problem.”
Parrish, S. (2010). Number talks: Helping children build mental math and computation strategies, grades K-5. Sausalito, CA: Math Solutions.
20 – 104 - 6
24 – 1623 – 15
30 – 106 - 9
36 – 1933 – 16
40 – 208 - 9
48 – 2944 – 26
50 – 103 - 7
53 – 1754 – 26
60 – 306 - 8
66 – 3864 – 29
70 – 402 - 5
72 – 4577 – 28
80 – 401 – 8
81 – 3883 – 44
90 – 506 – 7
96 – 5793 – 68
Category 3“Category 3 provides opportunities for students to use and extend the targeted strategy.”
Parrish, S. (2010). Number talks: Helping children build mental math and computation strategies, grades K-5. Sausalito, CA: Math Solutions.
0 – 6100 – 40 100 – 46100 – 19
100 – 0020 – 80
5 – 7125 – 87114 – 75
200 – 10010 – 20
5 – 6215 – 126223 – 134
300 – 10050 – 80
7 – 8357 – 188321 – 233
400 – 20040 – 50
4 – 6444 – 256412 – 135
500 – 3000 – 50 0 – 8
500 – 358500 – 263
600 – 30050 – 60
0 – 5650 – 365612 – 248
800 – 60050 – 90
3 – 4853 – 694826 – 437
1000 – 7000 – 10 0 – 5
1000 – 7151000 – 674
