1. Adding and Subtracting Whole Numbers

2. Benchmark  MA.2.A.2.1: Recall basic addition and related subtraction facts.  MA.2.A.2.2: Add and subtract multi-digit whole numbers through three digits with fluency by using a variety of strategies, including invented and standard algorithms and explanations of those procedures.

3. Objectives  Review of basic addition facts and related subtraction facts.  Develop fluency with multi-digit addition and subtraction.

4. Sample Problems  One day Juliana swam 4 laps. The next day she swam 3 more laps. How many laps did she swim altogether?  Nicole made a necklace. She used 13 red beads. She used 28 blue beads. How many beads did she use altogether?  There are 24 muffins in all. 15 muffins are on the plate. How many muffins are not on the plate?

5. What is Addition?  Addition is just a final count of numbers or items.  The result of an addition is called the “sum.”  Example: 3 + 4  This is the addition of 3 and 4 or 3 plus 4  Addition is represented as shown: 3 + 4  We can count on to get the sum 3  4, 5, 6, 7so the sum is 7 4

6. Examples : Write the sums  5 + 4 = ___  4 + 5 = ___  8 + 2 = ___  2 + 8 = ___  7 + 0 = ___

7. Word Problem  Roger build 4 toy airplanes. Then he builds 3 more toy airplanes. How many toy airplanes does he build together?

8. Make-A-Ten Strategy 4 9 3 + + 1 Think: - + 10 13

9. Try This! 9 + 4 =

10. The answer is: 10 + 3 = 13

11. Subtraction Facts  Subtraction is removing some objects from a group.  The meaning of 5 – 3 = 2 is "Three objects are taken away from a group of five objects and two objects remain".  Examples: 6 - 2 = 4 9 - 3 = 6

12. Subtraction Example  Example: 8 - 3  This is the subtraction of 3 from 8 or 8 minus 3  Subtraction is represented as shown: 8 - 3  We can count down to get the difference 8  7, 6, 5 so the difference is 5 3

13. Relationship between Addition and Subtraction  There is an inverse relationship between addition and subtraction.  If a math fact is considered, for example 3 + 7 = 10. Then the following are also true:  10 - 3 = 7  10 - 7 = 3  Similar relationships exist for subtraction, for example 10 - 3 = 7. Then the following are also true:  3 + 7 = 10  7 + 3 = 10

14. Review Examples  Sierra ate three cereal bowls in the morning. She ate the same number of bowls in the afternoon. How many bowls did she ate altogether?  Erin and Chase played many games of checkers. Erin won 11 games. Chase won 7 games. How many games did Erin win than Chase?

15. Let’s add large numbers. 12 and 34Line up numbers 12 + 34 Line up the digits on top of each other starting with the number on the right (the rightmost digit, which is called the “ones” place.)

16. Let’s add large numbers. 12 and 34Line up numbers 12 + 34 6 Line up the digits on top of each other starting with the number on the right (the rightmost digit, which is called the “ones” place.) Then add the numbers that are on top of each other like you normally would add numbers.

17. Let’s add large numbers. 12 and 34Line up numbers 12 + 34 6 Line up the digits on top of each other starting with the number on the right (the rightmost digit, which is called the “ones” place.) Then add the numbers that are on top of each other like you normally would add numbers.

18. Let’s add large numbers. 12 and 34Line up numbers 12 + 34 46 Line up the digits on top of each other starting with the number on the right (the rightmost digit, which is called the “ones” place.) And do the same for the other column of numbers.

19. Adding larger numbers... You may have to “carry” numbers to the next column of numbers being added if the first column is over 9. 2 3 1 + 4 5 9

20. Adding larger numbers... You may have to “carry” numbers to the next column of numbers being added if the first column is over 9. 2 3 1 + 4 5 9 0 Since 9+1=10, we will write the last digit of 10 (the zero) and “carry” the one above the 3 to the left to add it.

21. Adding larger numbers... You may have to “carry” numbers to the next column of numbers being added if the first column is over 9. 2 3 1 + 4 5 9 0 Since 9+1=10, we will write the last digit of 10 (the zero) and “carry” the one above the 3 to the left to add it. 1

22. Adding larger numbers... You may have to “carry” numbers to the next column of numbers being added if the first column is over 9. 2 3 1 + 4 5 9 0 Now we will add the 3 and 5, and also the 1 since it was carried over. 1

23. Adding larger numbers... You may have to “carry” numbers to the next column of numbers being added if the first column is over 9. 2 3 1 + 4 5 9 9 0 Now we will add the 3 and 5, and also the 1 since it was carried over. 5+3+1=9 We do NOT need to carry here. 1

24. Adding larger numbers... You may have to “carry” numbers to the next column of numbers being added if the first column is over 9. 2 3 1 + 4 5 9 9 0 Now we will add the 2 and 4 that in the far left column. 1

25. Adding larger numbers... You may have to “carry” numbers to the next column of numbers being added if the first column is over 9. 2 3 1 + 4 5 9 6 9 0 Now we will add the 2 and 4 that in the far left column. 2+4=6 1

26. With some practice, you will be able to successfully add positive whole numbers! This will be useful in all aspects of this class AND in your everyday life. Let’s look at a real-world example...

27. You graduated from Broward College!!!! As some of your graduation gifts, you receive gifts from family and friends with the values of $50, $129, $78, and $23. What is the total value of these gifts?

28. You will simply need to ADD all of those numbers up to get the total. 5 0 1 2 9 7 8 + 2 3 0

29. 5 0 1 2 9 7 8 + 2 3 0 Keep in mind to line up the places, add each column, and carry if the number has more than one digit! 0+9+8+3=20 2

30. 5 0 1 2 9 7 8 + 2 3 8 0 Keep in mind to line up the places, add each column, and carry if the number has more than one digit! 2+5+2+7+2=18 2 1

31. 5 0 1 2 9 7 8 + 2 3 2 8 0 Keep in mind to line up the places, add each column, and carry if the number has more than one digit! 1+1=2 2 1