Hi.....

.Net have lot of functions like these...... ".Net is an Ocean"

below few examples........

Converting decimal to binary in C#.NET
int a = 12;
MessageBox.Show(Convert.ToString(a, 2));

Converting decimal to octal in C#.NET
int a = 12;
MessageBox.Show(Convert.ToString(a, 8));

Converting decimal to HexaDecimal in C#.NET
int a = 12;
MessageBox.Show(Convert.ToString(a, 16));