Sigma of a single Variable with different values?

[mpdezfouli]

Hello all
My problem is that I have a variable that in an step by step program gives different values in each step, now I have to sum all this values as a new variable but I can not do it.
Please Help

[MikeyBoy]

Create a new variable to hold a running total of the variables.

At each step, add the current value to the running total.

Once all steps are complete, you'll have your sum.