Format solution to display a proper number of significant digits (see the VBA Format function). The VBA code does not need to decide how many digits to display.

Private Sub Reynolds_Click() Dim RE As Single, Q As Single, p As Single, D As Single, fv As Single, V As Single, m As Single Dim a As String, message1 As String

a = InputBox("Enter Equation Type", "Reynolds Number", "volumetric, velocity, or mfr") Select Case a Case "volumetric" Q = InputBox("Enter volumetric flow rate (m^3/sec)", "Reynolds Number", "1") p = InputBox("Enter fluid density (kg/m^3)", "Reynolds Number", "1") D = InputBox("Enter tube inside diameter (m)", "Reynolds Number", "1") fv = InputBox("Enter fluid viscosity (kg/msec)", "Reynolds Number", "1") RE = (4 * Q * p) / (WorksheetFunction.Pi * D * fv)