#### 1

- Chinese mathematician Liu Hsin uses decimal fractions.

#### 20

#### 60

- Heron of Alexandria writes
*Metrica* (*Measurements*). It contains formulas for calculating areas and volumes.

#### 90

- Nicomachus of Gerasa writes
*Arithmetike eisagoge* (*Introduction to Arithmetic*) which is the first work to treat arithmetic as a separate topic from geometry.

#### 110

- Menelaus of Alexandria writes
*Sphaerica* which deals with spherical triangles and their application to astronomy.

#### 150

- Ptolemy produces many important geometrical results with applications in astronomy. His version of astronomy will be the accepted one for well over one thousand years.

#### 250

#### 263

- By using a regular polygon with 192 sides Liu Hui calculates the value of π as 3.14159 which is correct to five decimal places. (See this History Topic.)

#### 301

- Iamblichus writes on astrology and mysticism. His
*Life of Pythagoras* is a fascinating account.

#### 340

#### 390

- Theon of Alexandria produces a version of Euclid's
*Elements* (with textual changes and some additions) on which almost all subsequent editions are based.

#### 400

- Hypatia writes commentaries on Diophantus and Apollonius. She is the first recorded female mathematician and she distinguishes herself with remarkable scholarship. She becomes head of the Neo-Platonist school at Alexandria.

#### 450

- Proclus, a mathematician and Neo-Platonist, is one of the last philosophers at Plato's Academy at Athens.

#### 460

#### 499

- Aryabhata I calculates π to be 3.1416. He produces his
*Aryabhatiya*, a treatise on quadratic equations, the value of π, and other scientific problems.