using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        decimal d1 = 124.73m;

        decimal d2 = EnsureDecimalPlaces(d1, 8); // 124.73000000

        Console.WriteLine(d1);

        Console.WriteLine(d2);

        Console.WriteLine(Convert.ToDouble(d2));

    }

    static decimal EnsureDecimalPlaces(decimal input, int decimalPlaces)

    {

        int currentPlaces = BitConverter.GetBytes(decimal.GetBits(input)[3])[2];

        int missingZeros = decimalPlaces - currentPlaces;

        return missingZeros <= 0 

            ? input 

            : input * GetMultiplier();

​

        decimal GetMultiplier()

        {

            return decimal.Parse($"1{NumberFormatInfo.CurrentInfo.NumberDecimalSeparator}{new string('0', missingZeros)}");

        }

    }

}