Calculator words

Type a word and you get the number to key in, here 0.7734. Turn the calculator over and it reads hello. The display is drawn both ways up so you can see it without a calculator. Swap the boxes to go the other way and see what any number says when turned over.

Only nine letters work, the ones a seven-segment digit looks like upside down. Words that use any other letter get an error naming the letters that won't go.

A calculator display builds every digit from seven bars. Turned through 180 degrees, some digits look like letters: 0 is O, 1 is I or l, 2 is Z, 3 is E, 4 is h, 5 is S, 6 is g, 7 is L, 8 is B and 9 is G. Together they spell BEghILOSZ, the whole alphabet available.

Turning the calculator over also reverses the order, so you key the word in backwards. A word that ends in O would need a leading zero, which calculators don't show, so it's typed with a decimal point. That's why hello is 0.7734 and not 07734.

Calculator spelling dates from the 1970s, and its best-known early example is a rude one. The Hollies used it in 1979 for an album titled Five Three One - Double Seven O Four, which spells hOLLIES. In the 1990s the same trick moved to numeric pagers, where 07734 was hello. The pager codes page has more of those.