Type 0.7734 into a calculator, turn it upside down, and it says hELLO. Generations of bored students have found this out for themselves, usually in a maths lesson, and it has been around for as long as pocket calculators have: the earliest printed examples we have found are from 1974.
The calculator alphabet
A calculator screen builds each digit from seven straight bars, called segments. Turned through 180 degrees, several digits happen to look like letters. Nobody designed it; it is a side effect of the display.
| Type | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
|---|---|---|---|---|---|---|---|---|---|---|
| Reads as | O | I | Z | E | h | S | g | L | B | G |
That gives nine usable letters: B, E, G, H, I, L, O, S and Z. Written in alphabetical order they spell beghilos, the nickname for the whole system. 6 and 9 give two versions of G, and 1 can pass for a capital I or a lower-case l.
The other 17 letters, from A to Y, are impossible. That includes A, D and T, so you cannot spell “Calculator Dad” on a calculator, which we take personally.
How to spell a word
- Write the word backwards. Turning the calculator over reverses the order, so you type the last letter first.
- Swap each letter for its digit using the table above.
- If the number starts with 0, put a decimal point after it. Calculators drop leading zeros, so 07734 would appear as 7734 and the O would vanish. Typing 0.7734 keeps it on screen.
Step 3 is the one most word lists get wrong. You will often see “zoo” given as 200. Type 200 and turn it over and you get OOZ. The right code is 0.02, which reads ZO.O. The same goes for logo (0.607, not 0607) and Ohio (0.140, not 0140). Every code on this page follows the rule.
Word finder
The famous ones
- 0.7734, hELLO. The one everyone is shown first. It was also a pager greeting in the 1990s: pager manuals told users they could send 07734 to say hello.
- 5318008, BOOBIES. The one everyone actually remembers. Slang dictionaries date it to the 1970s.
- 71077345, SHELL OIL. The oldest one we can find in print. During the 1974 oil crisis a puzzle did the rounds: 14,215,469 cars each use 5 gallons of fuel; multiply it out and turn the calculator upside down to see who wins. (14,215,469 × 5 = 71,077,345.)
- 7718, BILL. A 1977 newsletter for English teachers used calculator words as a vocabulary exercise: “7718 persons call him ____”.
- 0.40404, hOhOhO. What the calculator says at Christmas.
132 words you can spell
Codes are shown exactly as you would type them.
3-letter words
- bee338
- beg638
- big618
- bog608
- boo0.08
- ebb883
- eel733
- egg663
- ego0.63
- gee336
- gel736
- gig616
- goo0.06
- hoe304
- hog604
- ill771
- leg637
- lie317
- lob807
- log607
- loo0.07
- oil710
- see335
- she345
- sob805
- zoo0.02
4-letter words
- bees5338
- bell7738
- bile3718
- bill7718
- blob8078
- boil7108
- boob8008
- bosh4508
- boss5508
- bozo0.208
- else3573
- geez2336
- ghee3346
- gill7716
- glee3376
- glib8176
- goes5306
- gosh4506
- heel7334
- hell7734
- high4614
- hill7714
- hiss5514
- hobo0.804
- hole3704
- hose3504
- isle3751
- less5537
- lobe3807
- logo0.607
- lose3507
- loss5507
- oboe3080
- ogle3760
- ooze3200
- sell7735
- shoe3045
- sigh4615
- sill7715
- silo0.715
- size3215
- slob8075
- soil7105
- sole3705
- solo0.705
5-letter words
- beige36138
- belle37738
- bezel73238
- bible37818
- bilge36718
- bless55378
- bliss55178
- booze32008
- geese35336
- globe38076
- gloss55076
- goose35006
- hello0.7734
- igloo0.0761
- libel73817
- loose35007
- obese35380
- seize32135
- shell77345
- siege36315
- sizes53215
6-letter words
- bobble378808
- boogie316008
- giggle376616
- gobble378806
- google376006
- losses535507
- oblige361780
- obsess553580
- sizzle372215
- sleigh461375
Seven letters and up
- boobies5318008
- hobbies5318804
- hellish4517734
- legible3781637
- eggshell77345663
- eligible37816173
- hellhole37047734
- lossless55375507
- shoeless55373045
- bobsleigh461375808
- illegible378163771
- hillbillies53177187714
Names
- Bob808
- Bill7718
- Billie317718
- Bessie315538
- Eloise351073
- Elise35173
- Giles53716
- Leigh46137
- Leslie317537
- Lizzie312217
- Ollie31770
Places
- Ohio0.140
- Boise35108
- Oslo0.750
- Belize321738
- Lille37717
- Soho0.405
- Shiloh407145
Ohio is the only US state you can spell, and Boise, Idaho, is the only state capital. The Boise example was used on NPR's Sunday Puzzle in 2014.
We checked the whole dictionary
We took the 50,000 most-used words in English, from the open wordfreq frequency data, and kept the 26,812 that are real dictionary words of three letters or more. Then we tested every one against the calculator alphabet.
- 216can be spelled, about 1 in 124
- 71%of those are only three or four letters long
- 17letters of the alphabet can never appear, including A, T and N
The long ones are rare because every extra letter is another chance to hit one of the 17 impossible letters. On an ordinary 8-digit calculator, the longest words we found are eggshell (77345663), eligible (37816173), hellhole (37047734), lossless (55375507) and shoeless (55373045). A 10-digit scientific calculator adds illegible (378163771) and bobsleigh (461375808). The longest everyday word we found, hillbillies (53177187714), needs 11 digits, more than most calculators have.
A short history
Calculator words are as old as cheap calculators. The earliest example we found is in an amateur radio club newsletter from October 1974: the SHELL OIL puzzle above. By June 1975 the Associated Press was reporting that calculators had “spawned a new fad”, and puzzle books followed. Wallace Judd's Games, Tricks and Puzzles for a Hand Calculator (1974), Oleg Jefimenko's How to Entertain With Your Pocket Calculator (1975) and Norvin Pallas's Calculator Puzzles, Tricks and Games (1976) all use the trick, usually as a riddle: ask a question, do a sum, and turn the calculator over for the answer.
Teachers took it up quickly. Upside-down word exercises appear in American teaching guides for calculators from 1975 and 1977, and in a British school maths course in 1985.
The word beghilos is harder to pin down. The etymologist Michael Quinion wrote in 2009 that “nobody knows where it comes from”. It appears in the title of a 1988 paper at an Australian adult literacy conference, “Beghilos and the Pig Problem”, which is the earliest use we have found.
In 1979 the Hollies titled an album Five Three One – Double Seven O Four. Written as 5317704 and turned over, it spells hOLLIES. In April 2025 a New York Times Sunday crossword, “Numbers Game”, used eight upside-down calculator readouts as clues.
In other languages
The trick works wherever the Latin alphabet does, as long as the word avoids the missing letters. In German, 38317 spells LIEBE (love). In French, 3771350 spells OSEILLE, slang for money, which French students were typing in the early 1970s.
Why the display does this
Building characters out of straight bars is older than electronics. Carl Kinsley patented a telegraph printer that wrote letters and numbers in segments, filed in 1903, and Frank Wood patented a segmented display for showing gun-range data on warships in 1908. Seven-segment displays only became common in the 1970s, when LEDs and then LCDs made them cheap.
Seven bars are enough for the digits 0 to 9 and not much else, which is why only nine letters survive the flip. Calculators with 14- or 16-segment displays, like the HP-41 of the late 1970s, could show the whole alphabet the right way up, and nobody needed to turn them over. How the display is wired up is in our guide to what is inside a calculator.
Quick answers
How do you spell words on a calculator?
Write the word backwards, swap each letter for its digit (O=0, I=1, Z=2, E=3, h=4, S=5, g=6, L=7, B=8, G=9), and put a decimal point after a leading zero. Then turn the calculator upside down.
What does 0.7734 mean on a calculator?
Turned upside down, 0.7734 reads hELLO.
What letters can a calculator spell?
Nine: B, E, G, H, I, L, O, S and Z. The other 17 letters cannot be made with a seven-segment display turned upside down.
What is the longest word you can spell on a calculator?
On a standard 8-digit calculator, eight letters: eggshell, eligible, hellhole, lossless or shoeless. With more digits, illegible and bobsleigh (9) and hillbillies (11).
Why is zoo 0.02 and not 200?
Because the screen is read upside down. 200 turned over reads OOZ. 0.02 turned over reads ZO.O.
Sources
- Wikipedia, “Calculator spelling”; Wikipedia, “Seven-segment display”
- Yellow Thunder Smoke Signals, October 1974 (the SHELL OIL puzzle)
- Associated Press, in the Sikeston Daily Standard, 5 June 1975
- Wallace Judd, Games, Tricks and Puzzles for a Hand Calculator (Dymax, 1974); Oleg D. Jefimenko, How to Entertain With Your Pocket Calculator (1975); Norvin Pallas, Calculator Puzzles, Tricks and Games (Sterling, 1976).
- Minicalculators in the Classroom (National Education Association, 1977)
- Michael Quinion, World Wide Words, “Beghilos” (2009); Cherrie Hawke, “Beghilos and the Pig Problem” (1988)
- Wikipedia, “Five Three One – Double Seven O Four”
- NPR, Sunday Puzzle, 21 September 2014; XWord Info, NYT crossword of 27 April 2025
- Paul Dickson, Slang (1998), and RadioShack pager manuals, on 07734.
- US patent 1,126,641 (Kinsley, filed 1903); US patent 974,943 (Wood, filed 1908)
- Word counts: Calculator Dad analysis of the 50,000 most frequent English words in wordfreq (Robyn Speer), filtered against Webster’s Second International and GCIDE, September 2026.