If your using ng-repeat $index works like this
name="QTY{{$index}}"
and
<td>
<input ng-model="r.QTY" class="span1" name="QTY{{$index}}" ng-
pattern="/^[\d]*\.?[\d]*$/" required/>
<span class="alert-error" ng-show="form['QTY' + $index].$error.pattern">
<strong>Requires a number.</strong></span>
<span class="alert-error" ng-show="form['QTY' + $index].$error.required">
<strong>*Required</strong></span>
</td>
we have to show the ng-show in ng-pattern
<span class="alert-error" ng-show="form['QTY' + $index].$error.pattern">
<span class="alert-error" ng-show="form['QTY' + $index].$error.required">