Vertical Addition by Partition with 2-digit Numbers 18 + 17 20 (10 + 10) Add the tens 15 (8 + 7) Add the units 35 Vertical Addition by Partition with 3-digit Numbers 816 + 314 1100 (800 + 300) Add the hundreds 20 (10 + 10) Add the tens 10 (6 + 4) Add the units 1130 |