Little Isabella Little Isabella Little Isabella is a rustic water wheel, situated in Groudle Glen on the Isle of Man, that was originally built in 1893 with the arrival of the Manx Electric Railway to the glen. It has been dubbed the "Little Isabella" owing to its alleged resemblance to the Laxey Wheel in nearby Laxey which was opened in 1854 by Lady Isabella, the wife of the then Lieutenant Governor of the island. In its time the wheel has been used for various purposes, including pumping water to the Groudle Hotel (designed by Hugh Ballie-Scott) and providing power for the fairy
Largest known prime number Largest known prime number The largest known prime number () is 2 − 1, a number with 23,249,425 digits. It was found by the Great Internet Mersenne Prime Search (GIMPS) in 2017. Euclid proved that there is no largest prime number, and many mathematicians and hobbyists continue to search for large prime numbers. Many of the largest known primes are Mersenne primes. , the seven largest known primes are Mersenne primes. The last sixteen record primes were Mersenne primes. The fast Fourier transform implementation of the Lucas–Lehmer primality test for Mersenne numbers is fast compared to other known primality tests