int DecimalValue;
string ValueInBinary;
ValueInBinary= Convert.ToString(DecimalValue, 2); //DecimalValue in integer type is converted to a string in binary - base of 2 form 'ValueInBinary'

https://msdn.microsoft.com/en-us/library/8s62fh68(v=vs.110).aspx

Microsoft Official Documentation:
https://msdn.microsoft.com/en-us/library/8s62fh68(v=vs.110).aspx

C# - Convert decimal value of integer type to binary value of string type

convert, c#

C#