What mathematicians and clever parents do in the car


We live in a sprawling community and spend a lot of time in the car driving from activity to activity. While I am all about having time to stare out the window and daydream, we often make use of driving time for learning as well. One day, on a whim, I came up with a few mental math games to play in the car, mainly to give myself a break from playing guess-the-animal with my preschooler for the hundredth time. These have been a real hit with my kids and have allowed us to play with some serious math concepts. I thought your family might enjoy them too.

Mystery number

Player 1 thinks of a number and picks a (preferably silly) name for it. Then they put it into an equation. Player 2 then has to figure out the number.

Simple examples:

“My mystery number is Ooga Booga. Ooga Booga plus one is three. What is Ooga Booga?”

“My mystery number is Ice Cream Sandwich. Ice Cream Sandwich take away three is two. What is Ice Cream Sandwich?”

A little harder:

“My mystery number is Foosball. 238 take away Foosball is 92. What is Foosball?”

“My mystery number is Triceratops. Two Triceratops plus 32 equals 75. What is Triceratops?”

“My mystery number is Zebra Tail. One-third of Zebra Tail minus 4 is zero. What is Zebra Tail?”

We take turns making up questions. The kids particularly enjoy coming up with names for their mystery numbers and trying to stump Mom and Dad. Now that my oldest’s math skills have advanced, I have had to put a hold on the game when I really need to concentrate on the traffic or going somewhere new. I can’t focus on triple digit (or more) complex problems and my driving at the same time. But it is still a great game for the inevitable time in the car and we still play often.

We have been playing this game with our kids from around age four on. I have recently come across other math bloggers suggesting similar games, so I think we are onto something here. Our family’s silly twist of giving the numbers fun names makes it extremely engaging.  Allowing occasional potty words as the mystery number’s name makes it hilarious for the 5-6 year-old-set.  And occasionally using a letter name (n, x, etc.) as the mystery number’s name sets the stage for algebra later.

You can make problems as complex as you want.  Your mystery number can show up in the problem more than once (i.e. The square root of Chickadee plus 42 divided by Chickadee is…).  The mystery number can include fractions. You can create a system of equations with two mystery numbers.  You can create problems that require knowledge of order of operations.  When you play mystery number, you can meet your child wherever they are at mathematically. You help improve their (and your) mental math abilities and you demonstrate that math is a type of play, not something that just happens when you open up a textbook or workbook.

20 Questions, Guess the Number Version

The basics:

Player 1- Pick a number

Player 2-Ask yes or no questions until you figure out the number

Example questions:

Is it 7?

Is less than ___?

Is it greater than ___?

Is it odd or even?

Does it end in ___?

Is it a multiple of ___?

Is it divisible by __?

Is it positive?

Is it an integer?

Is it prime?

Is it a rational number?

Is it imaginary? (We haven’t gotten to this one yet)

I am sure you can think of more.

It is fun to see your kids develop mathematical understanding as they sort out the most efficient order for asking questions in order to eliminate the greatest number of possibilities at time.


Do you have any other verbal math games your family enjoys? Please let me know how it goes if you try these games with your kids!

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