Jamshid al-Kashi

Known for

Calculated π correct to 16 decimal places (1424); work on decimal fractions

Biography

Persian mathematician from Kashan invited to Samarkand by Ulugh Beg to work at his observatory.

Contributions

• Computed π to 16 decimal places, a record that stood for about 180 years
• Used and explained decimal fractions systematically
• Gave a form of the law of cosines used in trigonometry

Major works

• Al-Risala al-Muhitiyya (Treatise on the Circumference)
• Miftah al-Hisab (Key of Arithmetic, 1427)