60 (number) geometry, it is the number of seconds in a minute, and the number of minutes in a degree. In normal space, the three interior angles of an equilateral triangle each measure 60 degrees, adding up to 180 degrees. Because it is divisible by the sum of its digits in base 10, it is a Harshad number. A number system with base 60 is called sexagesimal (the original meaning of "sexagesimal" is sixtieth). It is the smallest positive integer that is written with only the smallest and the largest digit of base 2 (binary), base 3 (ternary) and base 4 (quaternary).
Schwarz triangle function a vertex of the polygon "P" makes an angle of less than 2/3 with each of the edges of the polygon at that vertex if exactly two triangles of "P" meet at the vertex, since each has an angle less than or equal to /3 at that vertex. To check this is true when three triangles of "P" meet at the vertex, "C" say, suppose that the middle triangle has its base on a side "AB" of "P". By induction the radii "OA" and "OB" makes angles of less than or equal to 2/3 with the edge "AB". In this