Weird thing I apparently have in common with my mother:

[conuly]

I don't remember how it came up, but a few days ago she commented that 51 isn't a prime number, even though it sure feels like it ought to be one.

I feel the exact same way!

And it's really silly, because 51 = 3 x 17 (I memorized it because I got tired of confusing it for a prime number) and it should be obvious with any two digit number whether or not those digits add up to a multiple of 3. (And in a base 10 system, if they do, that means the number is divisible by 3 and, of course, not prime.)

Nevertheless, even after memorizing the factors, I can never quite shake the feeling that 51 ought to be a prime number. And apparently, neither can Mommy.

Comments

[conuly]

111 certainly doesn't feel even a little prime, because of course it's a triple digit, and anytime you have the same digit repeated three times it MUST be divisible by three, ergo, not prime.

And of course 201 is just 21 with a 0 in the middle.