C#

public interface IMath<T>
{
    double CalculateDifference(T from, T to);
}
public class TestMath : IMath<int>, IMath<double>, IMath<datetime>
{
    #region IMath<int> Members

    public double CalculateDifference(int from, int to)
    {
        return to - from;
    }

    #endregion

    #region IMath<double> Members

    public double CalculateDifference(double from, double to)
    {
        return to - from;
    }

    #endregion

    #region IMath<datetime> Members

    public double CalculateDifference(DateTime from, DateTime to)
    {
        return (to - from).TotalSeconds;
    }

    #endregion
}

TestMath testMath = new TestMath();
Console.WriteLine(testMath.CalculateDifference(DateTime.Now, DateTime.Now.AddDays(1)));