Number Talks

 Addition and Subtraction

1) Decompose/ "Place Value" Addition Strategy

   39+26

   30+20=50

   9+ 6=   15

               65

     88 + 94

     90+80= 170

    8 + 4=     12

    170 + 12 = 182

    59-38

    50-30=20

         9-8= 1

                 21

    

    114-96

    100-90=10

         14-6= 8

    10 + 8 =18

Multiplication

1) Friendly Factors

    27(4)

    Decompose 27 into 20 + 7 then multiply by 4

    4(20)= 80

     4(7)     = 27

    80 +27 = 108

2) Partial Products

23 X 59

                  20     +   3

50  

 

+

9 

 1000    

 180

 150

 27

2) Adding to 10 (make both terms a 10)

    44+82

    40+80=120

Subtract 4 to get 40 and 2 to get 80

  4+2=6

  120+6=120

                  1180 + 177 = 1357

3) Doubling/Halving

64 (16)

16/2   =     8 (Divided By 2)

60(8)  =  480

8(4)    =    32

            512

512 (2)= 1024 (have to multiply by 2 since you divided  at the start.

3) Anchoring to 10 (when make one term a 10)

       86+ 62

       90 +62= 152

                         -4

                       148 

    

I added 4 to get 90, so I have to subtract 4 from 152. 

4) Compensation

    39+ 26

    +1    -1

     40 + 25= 65

    88 +94

     +2    -2

    90+ 92

        182

5) Doubles

    26 + 24

      -1    +1

     25 +25=50

    88+ 94

     +3   -3

    91 +91

        192

6) Counting On

59-38

38 (+2) =40 (+10) =50 (+9) =59

Add 2+10+9= 21

114-96

96 (+4) = 100 (+14)= 114

 4+ 14= 18

7) "Place Value" Subtractions Strategy

Subtract by counting back by 100, then 10 and 1

425-161 ?