Orderby numbers issue

Hi

I am using the Posts shortcode and trying to order them by numbers lowest to highest, in this case by price i.e.

7.50
11.60
13.40
etc

However the result comes out as

11.60
13.40
7.50

Now of course if I add a 0 before the 7 it comes out correctly but it is not practical to do so in this situation.

The price in this case is a meta key value.