Another mathematician, Carl Friedrich Gauss, echoed Archimedes when in 1796 he wrote in his diary, "ΕΥΡΗΚΑ! num = Δ + Δ + Δ", referring to his discovery that any positive integer could be expressed as the sum of at most three triangular numbers. This result is now known as Gauss' Eureka theorem and is a special case of what later became known as the Fermat polygonal …

The power number N p (also known as Newton number) is a commonly used dimensionless number relating the resistance force to the inertia force.. The power-number has different specifications according to the field of application. E.g., for stirrers the power number is defined as: = with P: power; ρ: fluid density; n: rotational speed in revolutions per second ; D: diameter …