Automator Droplet

You can do this with an Automator workflow and a script (I'm using Python, but it could be done with Bash, Applescript or anything else really).

1. Open up Automator, and choose Application type.
2. Add a Run Shell Script action to the workflow.
3. In the Run Shell Script action, set the Shell option to /usr/bin/python, and Pass input: to as arguments.
4. Set the script text to the script as shown below. Be sure to change the destination path to your desired destination.
5. Save the application to your desired location.

Script

import sys
import os
import subprocess

destinationPath = '/Users/rob/Desktop/test'

for f in sys.argv[1:]:
    name = os.path.basename(f)
    newdir = os.path.join(destinationPath, name[:1], name[:2], name[:3])
    print newdir

    if not os.path.exists(newdir):
        os.makedirs(newdir)

    subprocess.call(['mv', f, os.path.join(newdir,name)])
#eof

Important: Change the destinationPath = line to the path you want (i.e. the folder that contains your numbered folders). Make sure to retain the single quotes around the path.

Usage

Just drag and drop the files you want onto the application file you saved, and they'll be moved accordingly. If the proper folders don't exist already, they will be created.

You can use the following Apple Script to set a variable (named item_count) to the number of items returned from the previous action:

on run {input, parameters}
    set (value of variable "item_count" of front workflow) to (count of input)
    return input
end run

The list of items is simply passed through.

You could use it like this: