P5 Whole Numbers -- Addition of Series (1) (Fr CCL)

A. 1 + 2 + 3 + ... + 7 + 8 + 9
B. 1 + 2 + 3 + ... + 8 + 9 + 10

1. 1 + 2 + 3 + 4 ... + 2015
2. 2 + 4 + 6 + 8 ... + 2014
3. 4 + 7 + 10 + ... + 2017