| Vertical Addition by Partition with 2-digit Numbers 68 + 47 100 (60 + 40) Add the tens 15 (8 + 7) Add the units 115 Vertical Addition by Partition with 3-digit Numbers 309 + 830 1100 (300 + 800) Add the hundreds 30 (0 + 30) Add the tens 9 (9 + 0) Add the units 1139 |