1. Partial Sums An Addition Algorithm

2. 600 Add the tens (60 +80) 140 Add the ones (8 + 3) 751 Partial Sums 2 6 8 + 4 8 3 Add the hundreds ( 200 + 400) Add the partial sums (600 + 140 + 11) + 11

3. 1300 Add the tens (80 +40) 120 Add the ones (5 + 1) 1426 Let's try another one 7 8 5 + 6 4 1 Add the hundreds ( 700 + 600) Add the partial sums (1300 + 120 + 6) + 6

4. 1200 100 1318 Do this one on your own Let's see if you're right. Well Done! 3 2 9 + 9 8 9 + 18