(a) The Mesopotamians counted by sixties and their system was Sexagesimal. They knew multiplication. They divided time into minutes and seconds, and a circle into 360°. In Geometry they laid the foundation of the later Pythagoras theorem. In astronomy they calculated the length of the day and night, rising and setting of the Sun and Moon. The day was divided into 24 hours. They developed the Zodiac signs or Rashis. They invented the lunar calendar.

(b) The Egyptians developed a decimal system which helped in additions and subtractions. They calculated the area of a triangle and rectangle. They accurately calculated the solar calendar as 365 days. The year was di­vided into 12 months, each of 30 days. The extra 5 days were kept for religious festivals. Embalming the dead gave a stimulus to science and added to the knowledge of the structure of the human body and to skill in surgery.

(c) The Chinese brought out a calendar that was a combination of solar and lunar calendars, the months were lunar but the year was correctly calculated as 365 1/4 days. In astronomy they could foretell lunar eclipses,

(d) The high class Harappan pottery made on the potter’s wheel and the science of metallurgy which required knowledge of smelting and casting iron were highly developed.