Gerstenhaber was a child prodigy who was profiled in Leta Hollingworth 's book Children Above 180 IQ (1942). In this book, Gerstenhaber was dubbed "Child L," and his prodigious abilities and personality traits were described in great detail. At age 9 years 5 months, a Stanford-Binet test showed him to have a mental age of between 17 and 18 and an IQ between 195 and 198. A second revised Stanford-Binet given a year later found him to have a mental age of 19 years 11 months and an IQ of 199+.