How can I move text to a new line if it breaks the width of a box?

How can I move text to a new line if it breaks the width of a box?

Please take a look at this first: http://jsfiddle.net/TWbWx/2/
HTML:
<div class="box">
<div class="price">HUF129031290310</div>
</div>
CSS:
.box {
background-color:#00FF7F;
height: 300px;
width:120px;
}
What I want is when the price goes past the width of the box the numbers
should go under the currency. How can I do this? The first step is
separating the currency and the amount in separate divs but I'm unsure
where to go from there. Any help would be great.