1. Partial Sums An Addition Algorithm

2. 268+ 483 600 Add the hundreds ( 200 + 400) Add the tens (60 +80) 140 Add the ones (8 + 3) Add the place value sums (600 + 140 + 11) + 11 751

3. 785+ 641 1300 Add the hundreds ( 700 + 600) Add the tens (80 +40) 120 Add the ones (5 + 1) Add the place value sums (1300 + 120 + 6) + 6 1426

4. 329+ 989 1200 100 + 18 1318

5. This algorithm for addition is useful for adding multi- digit numbers. The partial sums are easier numbers to work with, students think about the value of each number, and students feel empowered when they discover that they can use this algorithm to add numbers mentally. This algorithm for addition is useful for adding multi- digit numbers. The partial sums are easier numbers to work with, students think about the value of each number, and students feel empowered when they discover that they can use this algorithm to add numbers mentally.