I would suggest using regexes:

var intRegex = /^d+$/;
var floatRegex = /^((d+(.d *)?)|((d*.)?d+))$/;

var str = $('#myTextBox').val();
if(intRegex.test(str) || floatRegex.test(str)) {
   alert('I am a number');
   ...
}

Or with a single regex as per @Platinum Azure's suggestion:

var numberRegex = /^[+-]?d+(.d+)?([eE][+-]?d+)?$/;
var str = $('#myTextBox').val();
if(numberRegex.test(str)) {
   alert('I am a number');
   ...
}

$("#myform").validate({
rules: {
field: {
  required: true,
  number: true
  }
 }
});

var ids=$('#Id').val();
if(isNaN(ids))
{
alert("Numbers only");
}

$("#myform").validate({
  rules: {
   field: {
    required: true,
    digits: true
   }
 }
});

$("#calculator").validate({
  rules: {
    filedName: { // u must replace filedName with ur textbox name (i assume ur textbox name is 'competitor-percent-fee')
      required: true,
      number: true
    }
  }
});

$("#calculator").validate({
  rules: {
    field: {
      required: true,
      number: true
    }
  }
});