Apologies: this page is somewhat awkward to use. Please bear with me until I can figure out a better way of doing it.
Identify the row and column "headers" (like in a spreadsheet) below. These are where you click. Clicking elsewhere has no effect. Use your Refresh or Reload button to start over.
Hints: What happens if you click on a column or row header repeatedly? What happens if the number of times you click for a given column (or row) is always either one more or one less than the number of times you click in the adjacent column (or row). Clicking 8 times is the same as not clicking at all, so the "arithmetic" of this page is "modulo 8". The color white comes up for two different numbers. End of hints! It will take some patience to create something here. The user-interface could be improved, but that will have to wait. Sorry there is no way to save your work, but you can print it!
JavaScript source and algorithms on this page are Copyright © 1989-2001 Kurt Karl Bigler, All Rights Reserved.