Sum of odd placed and even placed

#1

question:https://hack.codingblocks.com/contests/c/509/160
Answer:https://ide.codingblocks.com/#/s/24130

#2

There is no need of reversing the number. As given in explanation, for number 2635, 5 is at first place, 3 at second and so on.
Here is the correct solution:
https://ide.codingblocks.com/#/s/24244