Apparently a 12 years old boy came up with that algorithm: https://goodnigeria.com/chika-ofili-provides-solution-to-a-mathematics-problem/
@erou
And, substituting 2 with 9 and following the same procedure is the test for divisibility by 13. Although, I got no clue if the same 12 years old came up with this as well.
#math #maths #mathematics #divisibility #primes #primenumber #primenumbers
