Calculator Spelling


Mister L

This is one of my favorites.  It’s one of those nifty little activities that belong in every math teacher’s bag of tricks.  The basic idea is to solve a math problem with a calculator, then turn the display upside down.  The correct answer should spell out a word. It’s easy to do, a lot of fun and the kids love it.  In addition to building keyboarding skills, it rolls in a number of other topics, such as place value, properties of zero and one, order of operations, exponents, parenthetical expressions, integers, spelling and vocabulary.  It all depends how creative you want to get with it.


I used calculator spelling questions for warm-ups, bonus questions and time fillers. I always kept a dozen or so on hand that I could whip on the board in a hurry. It lends itself well to round robin activities. It’s particularly good for those high energy days like the day after Halloween or the day before Christmas break when everybody is wired. This is typically a noisy, active session with lots of LOL and OMG.  In my sessions, the students always ended up talking to each other and I was ok with that as long as the work was getting done and they weren’t sharing answers.

This is simple to set up and there are a lot of web sites that cover it.  Here it is in a nutshell.

The digits 0-9 can all be used as a letter when turned upside down.

0 = o or O

1 = l or i or I (big I, Little i, little L)

2 = z or Z

3 = E

4 = h

5 = s or S

6 = G

7 = L

8 = B

9 = g

Calculator answer

A TI-34 display showing the problem worked. Turn it upside down and check the answer. It may not jump out right away, but if it takes more than a few seconds to interpret, something’s wrong. That’s a very cool self-checking feature of this exercise.

So the word BELL would be 8377.  But remember, that’s what it looks like upside down, so the answer to the problem has to be 7738.  Then it’s just a matter of inventing a math problem that equals 7738.  It can be as simple or complex as you want to make it.  This is easily tailored to individual or class levels. I taught grades 6, 7 and 8. I could use the same answers to get the same words but the problem to get there would be different.

A variation is to have a question with a two or three word answer, which requires the students to correctly interpret and separate the words.  For instance, the answer 71077345 turned upside down becomes 54377017 or ShELLOiL.

Another variation is to use parentheses to get your answer but leave them out of the problem.  The students then have to place the (   ) in the correct place to get the correct answer.  It raises the challenge level and is self-checking – very cool.

Be careful with leading zeroes.  Most displays drop them.  So 07734 ( 43770 – HeLLO) becomes 7734 (4377 – HeLL).  To fix it, include a decimal point to fix the zero in the answer.

Just turn it upside down and read/interpret the answer. Sometimes, it doesn’t jump out at you. Make them stay with it. At some point, they may have to evaluate whether they have the right numbers. That’s part of the drill.

So how many words are there?  I have no idea. Here’s a Word List I compiled. It’s actually a couple of lists I condensed into one document.  You can make any word plural by adding -s or -es to the end.  You can create a descriptive word by adding -ish at the end.  Also, don’t forget abbreviations, nicknames, acronyms and even short foreign words.

The variations and innovations you can do with this simple activity are almost limitless.  It’s not the kind of thing you can do all the time, but when pulled out of your bag of tricks, it can be most productive.

Here are some links to other related resources.

Calculator Spelling NCTM Standards (so you can show your principal when they ask why you aren’t teaching the test)

Calculator Spelling Exercise 1

Calculator Spelling Exercise 2

Sometimes on the exercises, students will come up with the right word just from the clue.  That’s good, but they still need to do the problem and write the solution.

It also goes much smoother if everyone uses the same kind of calculator. If you are fortunate enough to have classroom calculators, this is a good time to use them.  That way, you know the little quirks of the displays and functions and can plan accordingly.  It’s also easier to correct keyboarding mistakes and make learning points to the whole class if they have the same box.

If that’s not possible, then be prepared to answer student questions on “their” calculator. My standard response was “What exactly won’t it do?”  Or “Where are you getting stuck?”  Or I’ll watch them while they run through the problem again.

This is one looc tsop. ha ha ha

This is a good exercise for wringing out all those new calculators at the beginning of the year.  Better to be confused here than at the next standardized test.

Feel free to copy and/or use any of the posted or linked material.

Hey Count.  You need to get out more.  This is what happens when you grade papers all night and all weekend. You start talking backwards.

I hope it’s ton gnihctac.

hu ho  … LretsiM