You can use the Math.Max Method (Double, Double) for this purpose.
It returns the larger of two double-precision floating-point numbers: https://msdn.microsoft.com/en-us/library/7x97k0y4%28v=vs.110%29.aspx
So the code will look like this:
using System;
class NumberComparer
{
static void Main()
{
Console.WriteLine("Please write the first number to compare: ");
double firstNumber = double.Parse(Console.ReadLine());
Console.WriteLine("Please write the second number to compare: ");
double secondNumber = double.Parse(Console.ReadLine());
double compareNumbers = Math.Max(firstNumber, secondNumber);
Console.WriteLine("Number {0} is greater",compareNumbers);
}
}
