Calculator Spelling

Calculator spelling is the technique of spelling words or phrases by solving a mathematics problem on a seven-segment calculator and then turning the display upside-down. To take an easy example, type "14" on your calculator and turn it upside down. It should read "hi".

Each of the ten digits can represent a letter when turned upside-down:

0	O
1	I
2	Z
3	E
4	h
5	S
6	g
7	L
8	B
9	G

This gives us nine different letters to work with (since 6 and 9 both look like the letter g when turned upside down). These letters are b, e, g, h, i, l, o, s, and z. So, any word including only those letters can be spelled on a calculator. There is just one caveat: Since calculators don't display leading zeroes, to write a word with an "o" at the end, you will need to use a decimal point. So, 0.7734, turned upside down, reads "hello". Nine letters isn't a lot to work with, but you can still make several words. Here is a list of 364 words you can spell with your calculator, including several proper names.

One fun recreation is to solve riddles by performing calculations and turning the calculator upside down. For example: What's white, round on top, flat on the bottom, cold on the outside, warm on the inside, and sometimes full of Eskimos? To find the answer, calculate (16 × 49 + 7) ÷ 10000, and turn the calculator upside-down. Often, a story is written around the numbers used in the calculation, as in the following:

• This one is from around 1973 and was created by Donald Knuth: The Arabs and the Israelis were at war. 337 Arabs [enter 337] and 337 Israelis [multiply by 337] were fighting over a square property 8,424 metres square [add 8424 × 8424]. Who won? [turn the calculator upside down]
• A woman went shopping. She bought 33 of one item [enter 33], 33 of another item [multiply by 33], and 53 of yet another item [multiply by 53]. She then bought one final item [add 1]. What did she end up getting? [turn the calculator upside down] or A woman went shopping. She bought 66 items that were square in shape [enter 66 × 66] and then 231 more items that were square in shape [add 231 × 231], and she then bought one more item [add 1]. What did she end up getting? [turn the calculator upside down]
• Where can you find 1 out of every 50 [1 ÷ 50] animals? [turn the calculator upside down]
• A student, having an essay due the next day, started writing it at 11:05 p.m. [enter 1105]. He had 9 pens [concatenate 9 to the previous number], but none of them worked. He had 17 pencils [multiply by 17] but they all needed to be sharpened. He had 2 markers [multiply by 2] but they were both pink. What did he use to write his essay? [turn the calculator upside down]
• This one requires a ten-digit display: There is a huge concert about to take place. A young man asks 29,434 women to go with him, but they all turn him down, saying he is too square [enter 29434 × 29434]. He asks another 64,120 women, but they all say the same thing [add 64120 × 64120]. Disappointed, he is thinking there will be one less [subtract 1] person at the concert. However, not wanting to be a square, [take the square root] he ends up joining the other 100,000 [divide by 100000] people at the concert. What does he do?
• An astronaut was at Cape Canaveral, Florida. He travelled 524 miles west [enter 524] and 614 miles south [multiply by 614]. He was still two miles away from his destination [add 2]. What was his destination? [turn the calculator upside down]
• Warning: This one is somewhat political and may not be appreciated by everyone. The United States invaded Iraq in 2003 [enter 2003]. This was their second invasion of Iraq [multiply by 2]. Over 3,145 American soldiers were killed. [add 3145]. Who benefited the most from the Iraq war? [turn the calculator upside down]

It can also be fun to write your own riddles. Give it a try and see if you come up with. If you create something good that you'd like to share, let me know.

If you have a scientific calculator, it may have some modes in which characters other than just the digits 0-9. You may want to see what these characters look like upside-down and try spelling new words with these.

More mathematics activities for kids.