Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click Dim s() As String s = Split(TextBox1.Text, vbCrLf) For i = 0 To UBound(s) If s(i) Like "time_0=*" Then s(i) = "time_0=" & Val(Split(s(i), "=")(1) * 2) Next TextBox1.Text = Join(s, vbCrLf) End Sub