Friday, May 13, 2016

Prove It

Can I add and subtract groups of ten by using simple addition facts?

1. 90 -50= 40            
9-5 =4
90-50=40


2. 20+60= 80
2+6=8
20 +60=80


3. 31-21= 10
3-2=1
30-20=10
31-21= 10


4. 35+20=
3+2=5
30+20=50
35+20=55

5.  22 +45=67
2+4=6
40+20=60
45+22=67

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