Christian Goldbach

On this day in 1690, mathematician Christian Goldbach was born in Königsberg, Prussia (now Kaliningrad, Russia). In 1728 his math acumen earned him a job tutoring Tsar Peter II. Goldbach made contributions to areas including curves and differential equations, but he’s best known for posing the conjecture that bears his name. In its original form, Goldbach’s conjecture said that every integer greater than 2 can be expressed as the sum of three prime numbers. But at that time, 1 was considered a prime number. So today, the conjecture states that every even whole number greater than 2 is equal to the sum of two prime numbers. (For example, 4=2+2, 28=17+11; see diagram for more.) While recent work has shown that Goldbach’s conjecture holds true all the way up to enormous numbers, nobody has proven that it holds for all even whole numbers greater than 2. A $1 million prize offered in 2000 to anyone who proved Goldbach’s conjecture went unclaimed when the contest expired in 2002. (Image credit: Adam Cunningham and John Ringland, CC BY-SA 3.0)

Date in History: 18 March 1690