A Curious Number

[Andy the Actuary]

A friend told me he would pick us up at 6:43PM to go to dinner. He pulled this number out of the air because I commonly state weird pick-up times ("I'm a round number iconoclast"). 643 has somewhat interesting properties, I observed.

643 is a prime number.

13 = 6 + 4 +3 is a prime number

7 = 6 + 4 -3 is a prime number

5 = 6 - 4 + 3 is a prime number

67 = 64 + 3 is a prime number

61 = 64 - 3 is a prime number

37 = -6 + 43 is a prime number

There may be other prime numbers that can be formed by the digits 6, 4, and 3 while respecting the order but 6:43 was approaching so I had to put my pencil down.

[J2D2]

Fascinating, Andy, but you worry me.

[david rigby]

Way too much time on your hands.

[Andy the Actuary]

Do not worry about me. I'm just as sane as the day I applauded as I watched the pigs eat my little sister.

[david rigby]

When you went to dinner, did you cut your pizza into 6, 4, or 3 slices?

[Andy the Actuary]

I get into arguments with friends about how much bigger a 16 in pizza is than a 12 inch. They say 33%; I argue 78%, because after all pi are squared and not round.

[Tom Poje]

I always cut into 3 pieces. not hungry enough to eat 6 pieces

[J2D2]

Reminds me of the time in college when I heard someone call for pizza. He asked them to cut it into 6 pieces, because he was too full to eat 8.