[Javascript] length property?

[Les & Paula Tingley]

I'm new to javascript and could use some help with a road block on a new
project.
I need to determine the number of characters (variable) from a text box
on a form.
then use the results in a calculation that gets passed to another form
field. The form is
part of a web page for a Motocross Graphics company. I need to calculate
price for some Racing Numbers. The Numbers are $1 each but the Customer
would order his/her number by the set (Whatever their number happens to
be). The owner of the Graphics company wants the user to simply put in
their number and have the sales price calculated from that field. I
already have figured out the script to remove any spaces that the user
might enter. I now need to determine the number of characters in the
field, multiply it times $1.00 to get the resulting sales price. I had
attempted to get them to allow me to use a drop down box where the
customer would select the number of digits that they wanted, but this
could lead to human error. Does anybody have any clue on how to do this?

Thanks,
Les