Here I am, solidly in my fifth decade of life and it has never occurred to me to play, let alone invent, a math game (in fact, I started to write fourth decade, then corrected myself and still had to doublecheck with my husband. That’ll tell you something about the distribution of mathematical abilities in this house). My children, however, have inherited math genes from their dad and so driving home from school we have conversations like this:

Ben: Think of a number less than 100 but an even ten (ie, ten, twenty, thirty, etc). Don’t tell me.
Me: Got it.
Ben: Multiply that number by two.
Me: OK.
Ben: Add your original number.
Me: Done.
Ben: Now subtract your original number.
Me: OK.
Ben: Divide that by your original number.
Me (starting to lose track): OK…
Ben: Did you get two?
Me, surprised and impressed: Yes, I did!

So, obviously the “add your original number” and “subtract your original number” is a bit of fill, but I’m still kind of impressed that the boy is inventing number games like this since the trick would never even occur to me.

It was inevitable that Eli would want to get in on the act. Here’s how the math games go when Eli invents them:

Eli: Think of a number. Don’t tell me!
Me: OK.
Eli: Equals.
Me: Honey, equals doesn’t change a single number.
Eli: I know! I like equals, it’s so simple! So, come on, equals. Don’t tell me!
Me: OK, equals.
Eli (demonstrating): Now, with your left hand, hold up your pink and ring finger. And with your right hand, put up your pink and your ring finger. And your thumb. Your thumb!
Me (grateful I’m not driving): OK.
Eli: Add the numbers to the number in your head.
Me: Add five?
Eli: Don’t tell me!
Me: I won’t, I’m just checking which numbers to add; my fingers?
Eli: Yeah, add your fingers.
Me: OK.
Eli (losing interest): Now… what happens?

Maybe Eli will be a little bit more like me after all.

Lately Ben does math in the car. He’ll ask, “What’s 83 times 12?” And Tony or I will say, “Can you figure it out?” And he does. His thinking through 2/3 + 1/4 occupied a good 15 minutes of a long drive recently, and that’s okay because he’s seven. I don’t believe his first grade teacher has even taught the kids fractions yet, let alone how to add them.

So now of course Eli wants in on the fun. The other day on the drive to school he asked, “What’s 3 divided by 2?” Before I could respond, Ben said, “Eli, do you know what ‘divided by’ means?”
“No.”
“Well,” said Ben, “It’s a kind of math process; do you know what ‘math’ is?”
“No.”
“Okay, well, math is numbers. 3 divided by 2 means, how many two’s fit inside three, and that’s one and a half. “
Eli was perfectly satisfied with that explanation, and for now I am, too. Maybe Ben can teach Eli long division, also…