I want my program to enter a decimal that will output in 4 decimal places by not rounding the inputed number
input: 0.6363636364
output: 0.6363
1 Answer
For completeness, since the OP requested a VB solution, here's the Decimal extension based on Tim Lloyd's answer to Truncate Two decimal places without rounding:
Module MyExtensions <System.Runtime.CompilerServices.Extension> Public Function TruncateDecimal(d As Decimal, decimals As Integer) As Decimal Select Case True Case decimals < 0 Throw New ArgumentOutOfRangeException("decimals", "Value must be in range 0-28.") Case decimals > 28 Throw New ArgumentOutOfRangeException("decimals", "Value must be in range 0-28.") Case decimals = 0 Return Math.Truncate(d) Case Else Dim IntegerPart As Decimal = Math.Truncate(d) Dim ScalingFactor As Decimal = d - IntegerPart Dim Multiplier As Decimal = Math.Pow(10, decimals) ScalingFactor = Math.Truncate(ScalingFactor * Multiplier) / Multiplier Return IntegerPart + ScalingFactor End Select End Function End Module Usage:
Dim Value As Decimal = 0.6363636364 Value = Value.TruncateDecimal(4) 
duplicatesuffer from possible overflow. The best answer to truncating to a specified number of digits is Tim Lloyd's answer to Truncate Two decimal places without rounding