David Kelly, taught the mathematical and social history of the number 17 during is 45 years of teaching. Upon retirement Hampshire College gave Kelly an unusual tribute. They changed their speed limit from 15 mph to 17 mph.
The Springfield Newspapers online edition, Masslive, quotes Professor Kelly on the importance of the number 17. Link to Masslive Article
Top 17 Sensational 17 Stats from David Kelly
The ancient Greeks knew how to construct squares, equilateral triangles, and regular pentagons with straightedges and compasses; in 1796 Carl Friedrich Gauss proved that the euclidean tools sufficed also for the construction of a regular 17-sided polygon.
Any sequence of fewer than 17 consecutive positive integers contains at least one number which has no divisor in common with any of the other numbers; the 17-term sequence {2184, 2185, ..., 2200} contains no such number.
You can color all the (136) edges joining pairs of 16 points with 3 colors without having 3 of the edges forming a triangle be all the same color; with 17 (or more) points, there must be a monochromatic triangle.
A cube can be cut along 7 edges and unfolded to make a cross; a tesseract or 4-dimensional hypercube can be cut along 17 2-dimensional faces and unfolded into a three-dimensional cross.
There are 17 muscles in a horse's ear.
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."
There are 17 columns on the long side of the Parthenon in Greece.
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.
Horses have recently been reported to distinguish among 17 facial expressions.
The 17th century was a great century for Japanese Haiku which has 17 syllables (comfortably spoken with a single breath).
17 is the smallest number of clues that can be provided for a 9x9 Sudoku puzzle to have a unique solution.
There are 17 ways to write 17 as a sum of primes.
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...)
To calculate a 17% tip, divide the bill by 6 (and round up by 0.33333...%).
Morris the Cat died at age 17, the average lifespan of a goldfish.
The 17-year locust.
There are almost 17 ounces in a pound.