5. There are 17 muscles in a horse’s ear.

6. Roman historian Plutarch records “The Pythagoreans also have a horror for the number 17, for 17 lies exactly halfway between 16, which is a square, and the number 18, which is the double of a square, these two, 16 and 18, being the only two numbers representing areas for which the perimeter equals the area.”

7. There are 17 columns on the long side of the Parthenon in Greece.

8. There are 17 mathematically distinct wallpaper patterns. Tilings in the Alhambra, a Moorish castle in Spain, and M.C.Escher’s tessellations exhibit all the 17 different combinations of translations, rotations, and reflections.

9. Horses have recently been reported to distinguish among 17 facial expressions.

10. The 17th century was a great century for Japanese Haiku which has 17 syllables (comfortably spoken with a single breath).

11. 17 is the smallest number of clues that can be provided for a 9×9 Sudoku puzzle to have a unique solution.

12. There are 17 ways to write 17 as a sum of primes.

13. 1/17 is the 1st reciprocal of a positive integer whose periodic decimal expansion contains all 10 digits. (1/7 = 0.142857 142857 … ; 1/11 = .090909…; 1/17 = 0.0588235294117647 0588235294117647…)

14. To calculate a 17% tip, divide the bill by 6 (and round up by 0.33333…%).

15. Morris the Cat died at age 17, the average lifespan of a goldfish.

16. The 17-year locust.

17. There are almost 17 ounces in a pound.

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