'How many octaves can the Great Buddha reach when playing piano?' 'What is the total length of the heavenly robes worn by the Agyo and Ungyo statues?' — Sangaku dedicated to Todai-ji Temple for Reiwa 8, students who created the problems are honored

The Japan Mathematics Certification Institute (located in Taito, Tokyo; Chairman: Shinobu Takada), which administers and operates the Practical Mathematics Skills Test 'Suken' (Mathematics Certification / Arithmetic Certification), held the '"Sangaku 1·2·3" Contest 2026 in Nara' (co-sponsored by the Nara City Board of Education). On March 20, 2026 (Friday), at the Great Buddha Hall of Todai-ji Temple in Nara City, students who created unique arithmetic problems were honored with Excellence Awards, and their original problems were dedicated to Todai-ji Temple as sangaku.

Since 2015, the Institute has continuously dedicated sangaku (*) to Todai-ji Temple as part of its mission to 'spark interest in arithmetic and mathematics' and 'eliminate math aversion while increasing math enthusiasm.' Through 2024, the Institute created the math problems related to Todai-ji Temple itself.

For the 11th sangaku dedication in 2026 (suspended in 2021 due to COVID-19 prevention measures), and following the previous year's event, the Institute held the '"Sangaku 1·2·3" Contest 2026 in Nara' to share these activities with a wider audience. Elementary and middle school students (including junior high attached to secondary education schools, and national/private schools) in Nara City were invited to submit arithmetic and math problems related to Todai-ji Temple and Nara City.

After rigorous judging, students from Nara City Ichijo High School Attached Junior High School and Nara City Sahoudai Elementary School were selected for Excellence Awards.

The two award-winning problems dedicated as sangaku for 2026 are: 'How many octaves can the Great Buddha reach at maximum when playing piano?' and 'What is the combined length in meters of the heavenly robes (ten'ne) worn by the Agyo and Ungyo statues?' On March 20, a sangaku unveiling (dedication) and award ceremony were held at the Great Buddha Hall of Todai-ji Temple, where certificates were presented to each honored student. Judges commented: 'The careful mathematical consideration given to defining an octave and setting the condition of infinite keys is commendable. Additionally, the unique perspective of focusing on the length of the heavenly robes rather than the height of the Great Buddha or the building makes for a highly attractive piece.'

Sangaku (*) — Ema (votive tablets) of traditional Japanese mathematics (wasan) dedicated at shrines and temples, a culture said to have spread uniquely in Japan during the Edo period. Though the problems are often challenging, it has been a beloved custom to give thanks to the gods and Buddha for the joy of solving them, and to pray for academic success.