A 1000-Year-Old Trick for Testing Divisibility by 37 Using Casting Out Nines

Learn about an ancient mathematical technique for determining divisibility by 37 in this 25-minute educational video. Explore the fascinating method of "casting out nines" - a traditional approach for verifying arithmetic calculations by adding digits until reaching a single number. Discover how this process connects to modular congruence and remainder-based mathematics, extending to casting out 99s and 999s. Master practical applications of these mathematical concepts through clear examples and step-by-step explanations, progressing from basic principles of casting out numbers to understanding complex divisibility rules. Delve into topics including modular arithmetic, division properties, remainders with 3, and casting out 11s, culminating in a comprehensive understanding of testing divisibility by 37.