Digital deletions is one of the original mathematical games described by John Conway
in his famous 1976 book On Numbers and Games.
As always with mathematical games, playing it is only part of the fun; the best part is discovering a winning strategy.
The game is very simple:
- A series of any length of digits is written down (not all digits have to be used and a digit may be used more than once). For practical reasons, the number of digits is limited here between 6 and 18.
- On a turn, a player can:
- change any one of the digits to a value that is less than its actual value (negative numbers are not allowed),
- or erase a zero and all the digits to the right of it.
- The player who removes the last digit loses the game.
. If you know of other programmed versions, please contact me
I am proud to announce that this page is referenced by the Drexel Math Forum.
Click a digit to change its value. A glowing green light appears underneath the chosen digit.
If the value of this digit is
- > 0, change it with a click on one of the green leds (you can change as often as you want),
- = 0, you can only click the OK button to remove it and all the digits to its right.
As long as you did not click the OK button, you can change your mind and choose another digit or another value.
After having calculated its move, the computer informs you about it with a glowing red light indicating the digit that has been changed and a panel, showing the old and the new value. Just click the digit you want to change to acknowledge the computer's move.