Perhaps you'd like to emply 'mates8.dll' (in the attached file there is an example). There needs to be a reference to the dll and the imports statement. Then, you may parse simple expressions calling the Expression.parseExpression method.
Imports m8 = mates8
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles btnCalculate.Click
Dim expr As m8.Expression = m8.Expression.parseExpression(tBoxExpression.Text)
tBoxResult.Text = expr.ToString
Catch ex As Exception