نظام العد الستيني (بالإنجليزية: Sexagesimal Numeral System) هو نظام عد قاعدته ستينية.[1][2][3] اخترع السومريون هذا النظام في الألفية الثالثة ق م، ونقلها عنهم البابليون، وهو ما زال مستخدمًا في قياس الزمن والزوايا الهندسية ونظام الإحداثيات الجغرافية.
الرقم 60 يمكن تحليله إلى 12 عدد، وهي { 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60 } من بينها 2، 3، 5 وهي أعداد أولية.
Neugebauer، O. (1969). The Exact Sciences in Antiquity. Dover. ص. 17, para. 3 (middle). ISBN:0-486-22332-9. مؤرشف من الأصل في 2022-04-19. In other words: it is only in strictly mathematical or astronomical contexts that the sexagesimal system is consistently applied. In all other matters (dates, measures of weight, areas, etc.), use was made of mixed systems which have their exact parallel in the chaos of 60-division, 24-division, 12-division, 10-division, 2-division which characterizes the units of our own civilization.
Neugebauer، O. (1969). The Exact Sciences in Antiquity. Dover. ص. 19, para. 2 (middle). ISBN:0-486-22332-9. مؤرشف من الأصل في 2022-04-19. Variations of these systems, both decimal and more or less sexagesimal, can be established at different localities. The main facts, however, are common to all of them, namely, the existence of a decimal substratum and the use of bigger symbols to represent higher units. This latter fact is obviously the root for the development of the place value notation.
Neugebauer، O. (1969). The Exact Sciences in Antiquity. Dover. ص. 17, para. 1. ISBN:0-486-22332-9. مؤرشف من الأصل في 2022-04-19. The other inconsistency of the modern astronomical notation, namely, to continue beyond the seconds with decimal fractions, is a recent innovation. It is interesting to see that it took about 2000 years of migration of astronomical knowledge from Mesopotamia via Greeks, Hindus, and Arabs to arrive at a truly absurd numerical system.