or SEXAGESIMAL Fractions, fractions whose denominators proceed in a sexageneric ratio; that is, a prime, or the first minute \(= \frac{1}{60}\); a second \(= \frac{1}{3600}\); a third \(= \frac{1}{216000}\). Anciently there were no other than sexagesimals used in astronomy; and they are still retained in many cases, though decimal arithmetic has come into use now in astronomical calculations. In these fractions, which some call astronomical fractions, the denominator, being always 60, or a multiple of that number, is usually omitted, and the numerator only written down. Thus \(4^\circ\), \(59'\), \(32''\), \(50''\), \(16''\), is to be read, 4 degrees, 59 minutes, 32 seconds, 50 thirds, and 16 fourths.