To reproduce: use the following code snippet  and try to input some numeric value

public RadForm1()
 {
     InitializeComponent(); 
     this.radMaskedEditBox1.MaskType = Telerik.WinControls.UI.MaskType.Numeric; 
     this.radMaskedEditBox1.ValueChanged += radMaskedEditBox1_ValueChanged;
 }

 private void radMaskedEditBox1_ValueChanged(object sender, EventArgs e)
 {
     Console.WriteLine(this.radMaskedEditBox1.Value);
 }