C# program that calculates percentsusing System; class Program { static void Main() {// Display percentage of visits that resulted in purchases.int purchases = 10; int visitors = 120; DisplayPercentage((double)purchases / visitors);// Display 50 percent with overloaded method.DisplayPercentage(1, 2);// Write percentage string of nine tenths.Console.WriteLine(GetPercentageString((double)9 / 10)); }/// <summary> /// This method writes the percentage form of a double to the console. /// </summary>static voidDisplayPercentage(double ratio) { string percentage = string.Format("Percentage is {0:0.0%}", ratio); Console.WriteLine(percentage); }/// <summary> /// This method writes the percentage of the top number to the bottom number. /// </summary>static voidDisplayPercentage(int top, int bottom) { DisplayPercentage((double)top / bottom); }/// <summary> /// This method returns the percentage-formatted string. /// </summary>static stringGetPercentageString(double ratio) { return ratio.ToString("0.0%"); } }OutputPercentage is 8.3% Percentage is 50.0% 90.0%

**Also:**The second DisplayPercentage accepts two parameters and then passes the ratio of them to the other method. It casts to double.

**Finally:**GetPercentageString accepts a double containing a ratio and returns a percentage string using ToString().

C# program that converts ratiosusing System; class Program { static void Main() {// We want to have 92.9% from these two numbers.int valid = 92; int total = 99;// First multiply top by 100 then divide.double percent = (double)(valid * 100) / total;// <-- Use cast // This is the percent number.Console.WriteLine(percent); Console.WriteLine(Math.Floor(percent)); Console.WriteLine(Math.Ceiling(percent)); Console.WriteLine(Math.Round(percent, 1)); } }Output92.9292929292929 92 93 92.9

**Tip:**With modulo division, we can run an operation every N times. This has uses in many programs.