public class ClasseViewModel
{
    [Required(ErrorMessage = "Campo Obrigatorio")]
    [Display(Name = "Campo Decimal")]
    public decimal? CampoDecimal { get; set; }
}

@Html.RequiredLabelFor(model => model.CampoDecimal, htmlAttributes: new { @class = "control-label" })
@Html.EditorFor(model => model.CampoDecimal, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.CampoDecimal, "", new { @class = "text-danger" })