i remember the 1110 thing on a calc as well. 741 + 369 & 963 + 147 | 123 + 987 & 321 + 789 (left right | up down) 159 + 951 & 753 + 357 | 258 + 852 & 456 + 65

i remember the 1110 thing on a calc as well. 741 + 369 & 963 + 147 | 123 + 987 & 321 + 789 (left right | up down) 159 + 951 & 753 + 357 | 258 + 852 & 456 + 654 (diagonally | center lines) the design of a keypad... it unintentionally contains these elegant mathematical relationships. i call this phenomena: outcomes of human creations can be "funny and odd", and everybody understand that eventually there will be always something unpredictable.