I have values entered into a column. In the next columns over I'd like to be
able to simply enter X or another marking value so that the numbers from that
row carry over without me having to enter in the number every time I want to
use it.

Example:
A B C D
1 X X
2 X X
3 X X X
4 X

So that either the X's turn into the numbers from column A or when I sum the
values at the bottom of columns B, C, and D they add up to 6, 5, and 8
respectively. Any help?