Hangmath © 1977 1001001, Inc.
A Hangman variant with a twist. Instead of guessing for a word a sum is displayed, but all the numbers are blanked out. To get started the player can reveal all numbers in a single column and make one free guess for another number. After that each incorrect guess counts and when the sum is revealed the player is graded on how well he or she did.
Released in April 1977.