Write down any 5 digit number that doesn't have all of the same number in it. Follow the steps in the project by clicking, tapping, or pressing any key. It will always be able to tell which digit you removed as long as you follow the instructions correctly. You will always get an example if you are unsure of what the prompt means.
I learned this trick from a book called "Mathematical Amazements and Surprises" by Alfred S. Posamentier and Ingmar Lehmann. Would definitely recommend if you love math. 100% coded by me, @74177Y
