using System;

public class Program

{

    public static void Main()

    {

        Random random = new Random();

​

        double max = 1.2;

        double min = 0.8;

        double step = 0.1;

        int increment = (int)Math.Truncate(random.NextDouble()*(max - min)/step);

        double value = min + step * increment;

        Console.WriteLine($"increment: {increment}, value: {value}");

    }

}