Riemann had exceptional mathematical talent, such as calculation abilities, from an early age but suffered from timidity and a fear of speaking in public he also had frail health.

He built 20 finished machines over the course of 10 years

-He laid the foundation of graph theory and topology while solving the problem of seven bridges of Königsberg

Euler's theorem

-Also known as the Euler-Fermat theorem or Euler’s totient theorem. This theorem is an extension of Fermat’s little theorem, which has a restriction of ‘n’ being prime.