Untitled

How do I make a div automatically wide enough to accomodate its floating children?
<div class="Parent"> <!-- 3 Children, should be 450px wide-->
  <div class="Child"></div>
  <div class="Child"></div>
  <div class="Child"></div>
</div>
<div class="Parent"> <!-- 2 children, should be 300px wide-->
  <div class="Child"></div>
  <div class="Child"></div>
</div>

.Parent {
    float: left;
    background: #ccc;

    margin: 0 0 16px 0;
    clear: both
}
.Child {
    float: left;
    width: 150px;
    height: 50px;
}