Note: Do not hold the left mouse button down as you drag the digits around. Just single click on the leading digit then release the mouse button and move the mouse. To drop the digit single click again.
A note to Netscape Users: Netscape sometimes does not pass the mouse click to the project when you go to drop the digit. Sometimes trying repatedly wil get the mouse click through. This problem doesn't happen if you copy the project to your machine and run it locally in MicroWorlds.