# Off the Number Line: Fear of the Number Thirteen

Interviewer:

I’m not sure I can even pronounce that… What is tris-kai-deka-phobia?

Cartoonist:

It means fear of the number thirteen. And it’s a real thing. I’ve been in lots of hotel elevators where the buttons are labeled 11, 12, 14, 15 and so on.

Interviewer:

They skip 13 because it’s unlucky.

Cartoonist:

There’s still a 13th floor, just now it’s called “14”. It’s not logical.

Interviewer:

I see. So in the cartoon, superstition is making 5 and 7 conclude that they can’t count on 13.

Cartoonist:

Of course they can count on 13. He’s a counting number. He’s a prime and part of the Pythagorean triple 5, 12, 13. He’s the only counting number that can be the fourth root of the sum of squares of two consecutive integers. They just turned down an awesome number!

Interviewer:

Well, it makes sense to make this a number 13 appreciation week because this is precisely the thirteenth edition of Off the Number Line Cartoons! Congratulations! And here’s to many more editions of math fun!

Is your child afraid of numbers, math and homework? Check out 12 Tips for Homework Without Tears.

Matthew Peterson, Ph.D., is Co-founder and Chief Research & Development Officer at the MIND Research Institute. James Huang is Senior Visual Designer at MIND Research Institute.

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