1. Addition Algorithms S. Matthews

2. Partial-Sums Method for Addition Add from left to right and column by column. The sum of each column is recorded on a separate line. The value of each digit is determined by its place in the numeral.

3. Let’s practice the value of digits for Partial-Sums. In the problem 23 + 45, we first add the 2 and 4. However, the 2 is worth 2 tens, and the 4 is worth 4 tens. So we say 20, not 2; and 40, not 4. In the problem 23 + 45, we first add the 2 and 4. However, the 2 is worth 2 tens, and the 4 is worth 4 tens. So we say 20, not 2; and 40, not 4.

4. Let’s practice the value of digits for Partial-Sums. Your turn. What do we say when adding the hundred’s place for 376 + 832? Your turn. What do we say when adding the hundred’s place for 376 + 832?

5. You’ve got it! We say 300, not 3; and 800, not 8. What is the sum of the 100’s place? You’ve got it! We say 300, not 3; and 800, not 8. What is the sum of the 100’s place?

6. Can’t fool you! In 376 and 832, the 3 is worth 300, and the 8 is worth 800. 300 + 800 is 1,100 or eleven hundred. Can’t fool you! In 376 and 832, the 3 is worth 300, and the 8 is worth 800. 300 + 800 is 1,100 or eleven hundred.

7. Let’s practice the value of digits for Partial-Sums. Let’s continue. What do we say when adding the tens place for 376 + 832? Let’s continue. What do we say when adding the tens place for 376 + 832?

8. That’s right! We say 70, not 7; and 30, not 3. What is the sum of the 10’s place? That’s right! We say 70, not 7; and 30, not 3. What is the sum of the 10’s place?

9. Can’t fool you! In 376 and 832, the 7 is worth 70, and the 3 is worth 30. 70 + 30 is 100 or ten tens. Can’t fool you! In 376 and 832, the 7 is worth 70, and the 3 is worth 30. 70 + 30 is 100 or ten tens.

10. Take a look at the steps for addition using the Partial- Sums Method. Then we’ll practice the method some more. Take a look at the steps for addition using the Partial- Sums Method. Then we’ll practice the method some more.

11. 398 + 435 Add the 100’s: 300 + 400 = + 13 Add the 10’s: 90 + 30 = Add the 1’s: 8 + 5 = Find the total 120 700 833

12. Now, you try the Partial- sums method using the numbers we practiced.

13. 376 + 832 Add the 100’s: 300 + 800 = + 8 Add the 10’s: 70 + 30 = Add the 1’s: 6 + 2 = Find the total 100 1100 1, 208

14. You are good! Let’s try just one more. You are good! Let’s try just one more.

15. 479 + 285 Add the 100’s: 400 + 200 = + 14 Add the 10’s: 70 + 80 = Add the 1’s: 9 + 5 = Find the total 150 600 764

16. Excellent! I know you’ve got the hang of it. Don’t forget, in the Partial-Sums method for addition, you: add the 100’s, add the 10’s, add the 1’s. Then add the sums you just found. (the partial sums) Excellent! I know you’ve got the hang of it. Don’t forget, in the Partial-Sums method for addition, you: add the 100’s, add the 10’s, add the 1’s. Then add the sums you just found. (the partial sums)

17. Keep practicing. Peace! Keep practicing. Peace!