How edit this ERROR from console code

You are multiplying fact with another value, but at that point in your code fact has not been initialised so it does not contain a valid number. You should add an initialisation statement before your loop, something like:

fact = 1;
// your loop starts here

Also, in future please post you code and the error message into your question, rather than a link to a screen shot.

Public static int fact =0 before using

Give it an initial value...
At present, you declare it, and then immediately use it to multiply by itself. Since it doesn't have a specific start value, VS rightly complains.

int fact = 1;

BTW: In future, don't be so lazy: copy and paste your code here (within a code block).
That way, if we need to compile or run it, we can - without having to type it in again ourselves. :doh:
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