Convert.ToByte (UInt64) converts 64-bit unsigned integer to 8-bit unsigned integer.
Class Sample Public Shared Sub Main() Dim numbers() As ULong = { UInt64.MinValue, 121, 340, UInt64.MaxValue } Dim result As Byte For Each number As ULong In numbers Try result = Convert.ToByte(number) Console.WriteLIne("Converted the {0} value {1} to the {2} value {3}.", _ number.GetType().Name, number, _ result.GetType().Name, result) Catch e As OverflowException Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", _ number.GetType().Name, number) End Try Next End Sub End Class