The divisibility rule for 9 can be extended for divisors composed entirely of 9s like 99, 999, 9999 etc. The rule for 9 is that “If the sum of the digits of the number is divisible by 9, then the…
Our 15th MATH-Inic Special for Christmas deals with divisibility of numbers. Grade school children are required to know by heart the divisibility rules for numbers such as 2, 3, 4, 5, 7, 8, 9, 10 and 11. Also a…
Yesterday, I read a post here in Facebook about a 12-year old Nigerian boy, Chika Ofili, who received a special recognition for discovering a new formula for divisibility by 7, while doing his holiday assignment. The book they are using…