Q:

Next Nearest Number Divisible By X

What I want to do essentially, is take any number a user has input, and round it to the next closest whole number divisible by X, excluding 1.
IE (X = 300):

Input = 1 Output = 300
Input = 500 Output = 600
Input = 841 Output = 900
Input = 305 Output = 300

A:

Just (integer) divide by X, add one, then multiply by X.
int output = ((input / x) + 1) * x;

A:

Based on your example behaviour I would do something like this:

double GetNearestWholeMultiple(double input, double X)
    {
      var output = Math.Round(input/X);
      if (output == 0 && input > 0) output += 1;
      output *= X;

      return output;
    }

