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| c. 250 BC |
| | | The Romans evolve a system of numerals which, until the end of the Middle Ages, is a handicap to western arithmetic | |
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| c. 220 BC |
| | | The Greek mathematician Eratosthenes calculates the circumference of the world with the help of shadows and camels | |
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| c. 140 BC |
| | | The Greek astronomer Hipparchus is credited with the invention of the astrolabe, measuring the angle of sun or star above the horizon | |
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| c. 130 BC |
| | | The Greek astronomer Hipparchus, mapping the stars, observes but cannot explain the precession of the equinoxes | |
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| c. 130 BC |
| | | Hipparchus proposes a grid of 360° of latitude and longitude for mapmaking | |
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| 129 BC |
| | | Hipparchus completes the first scientific star catalogue, mapping some 850 stars | |
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| c. 100 BC |
| | | The practice of acupuncture is described in Nei Qing, a Chinese medical text | |
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| c. 50 BC |
| | | The Maya independently develop the concept of place value in numbers, previously pioneered in Babylon | |
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| c. 50 BC |
| | | The Maya introduce a calendar which has a cycle of fifty-two years, known as the Calendar Round | |
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| 45 BC |
| | | Julius Caesar's new calendar is introduced, at a time when its predecessor has become out of step with the seasons by three months | |
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