1742 On June 7th, Goldbach wrote to Euler, a great mathematician at that time, and formally put forward the following conjecture: A. Any even number greater than 6 can be expressed as the sum of two prime numbers. B Any odd number greater than 9 can be expressed as the sum of three prime numbers.
This is Goldbach's conjecture. Euler wrote back that he believed the conjecture was correct, but he couldn't prove it.
Since then, this mathematical problem has attracted the attention of almost all mathematicians. Goldbach conjecture has therefore become an unattainable "pearl" in the crown of mathematics.
China mathematician Chen Jingrun proved in 1966 that any sufficiently large even number is the sum of a prime number and a natural number, which can be expressed as the product of two prime numbers. "Usually this result is expressed as 1+2. This is the best result of this problem at present.