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## Unit 2: Adding and Subtracting Whole Numbers

Unit 2: Adding and Subtracting Whole Numbers

The main topics of Unit 2 are addition and subtraction of whole numbers, the basic facts and their extensions, solution strategies for solving number stories involving adding and subtracting, and adding and subtracting multi-digit numbers.

Unit 2 Main Areas of Focus:

*To review fact families and number families

*To review and solve “What’s My Rule?” problems

*To use diagrams to help solve number stories

*To review algorithms for adding and subtracting

Daily Lessons:

2.1 Fact Families

2.2 Extensions of Addition and Subtraction Facts

2.3 “What’s My Rule?”

2.4 Parts-and-Total Number Stories

2.5 Change Number Stories

2.6 Comparison Number Stories

2.10 Progress Check 2

Subtraction Algorithms

Partial Sums
Partial sums first adds the hundreds, then tens, then ones, and then combines them to get a total.

329
+ 418

300+400= 700

20+10= 30

9+8= 17

747

The trade first method is also known as the traditional method. The only difference is that you do all the trading before subtracting.

12 14

3 2 4
+ 1 9 7

12 14

3 2 4
+ 1 9 7

2 3 7