Yutaka Nishiyama (西山 豊, Nishiyama Yutaka, born 21 October 1948) is a Japanese mathematician and professor at the Osaka University of Economics, where he teaches mathematics and information. He is known as the "boomerang professor".^[1] He has written nine books about the mathematics in daily life.^[2] The most recent one, The mystery of five in nature, investigates, amongst other things, why many flowers have five petals.

This biography of a living person needs additional citations for verification. (June 2012)

• 1967-1971: Faculty of Mathematics, Department of Science, Kyoto University
• 1971-1985: IBM Japan as a Systems Engineer
• 1985: Lecturer of Information Mathematics at Osaka University of Economics
• 1995–present: Professor at Osaka University of Economics
• 2005-2006: Visiting fellow at University of Cambridge, UK, joined for MMP.^[3]

• 50 Visions of Mathematics, Oxford University Press, May 2014, ISBN 978-0-19-870181-1
• The Mysterious Number 6174: One of 30 Mathematical Topics in Daily Life, Gendai Sugakusha, July 2013, ISBN 978-4-7687-6174-8

• General Solution for Multiple Foldings of Hexaflexagons IJPAM, Vol. 58, No. 1, (2010). 113–124. "19 faces of Flexagons"
• Fixed Points in Similarity Transformations IJPAM, Vol. 56, No. 3, (2009). 429–438.

• A bright idea, Plus Magazine, issue 36, University of Cambridge, September 2005.
• Mysterious Number 6174, Plus Magazine, issue 38, University of Cambridge, March 2006.
• Winning Odds, with Steve Humble, Plus Magazine, issue 55, University of Cambridge, June 2010.
• Having fun with unit fractions, Plus Magazine, University of Cambridge, Feb 2012.
• Circles rolling on circles, Plus Magazine, University of Cambridge, May 2014.