The oldest surviving mathematical text from this country concerned computation techniques using an   abacus and was titled the Jinko ki.
One group of three mathematicians from this country is known as the Three Arithmeticians, and Soddy's hexlet was independently discovered in this country in 1822. Another mathematician from this country used a system called  circle principles  to calculate limits like the area of a circle. The oldest surviving mathematical text from this country concerned computation techniques using an   abacus and was titled the Jinko ki. This country's practice of leaving geometric problems on wooden tablets as o erings at temples is known as sangaku. A mathematician from this country developed inter-universal Teichmüller theory while working at Kyoto University. For ten points, identify this country of Shinichi Mochizuki.
One group of three mathematicians from this country is known as the Three Arithmeticians, and Soddy's hexlet was independently discovered in this country in 1822.
Japan [accept Nippon-koku, accept Nihon-koku]