hi,
try following code for lost focus event
Private Sub TextBox1_Validating(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles TextBox1.Validating
Dim est As Decimal
If TextBox1.Text.Length = 0 then Exit Sub
If Not Decimal.TryParse(TextBox1.Text.Trim, est) Then
e.Cancel = True
TextBox1.SelectAll()
Else
TextBox1.Text = est.ToString("N0")
End If
End Sub
hope it will Help u
Best Luck
Happy Coding