Ingmar Lehmann is retired from the mathematics faculty at Humboldt University in Berlin. For many years, he led the Berlin Mathematics Student Society for gifted secondary school students, an organization with which he is still closely engaged today.
He is the author of numerous mathematics texts in Germany and the coauthor with Alfred S. Posamentier of some other books, including The Secrets of Triangles, The Glorious Golden Ratio, Magnificent Mistakes in Mathematics, and The Fabulous Fibonacci Numbers.
