Divisibility

An inexhaustible source of arithmetic marvels, divisibility criteria are far from all being known... and even further from being mastered! Everyone knows how to recognize an integer divisible by 2, 3, 5, 9 or 10 or by one of their products. Divisibility by 11 is already a bit less familiar. But what about divisibility by prime numbers such as 13, 17, 19, 23 or 29? Are you stumped? There are nevertheless simple tricks that make it possible to develop criteria for each of them. Since the 17th century, Pascal had developed some to help merchants. Other original algorithms continue to thrive today, such as those of Vosburgh Lyons.