birthday problem - SERP Analysis

https://en.wikipedia.org/wiki/Birthday_problem

https://www.reddit.com/r/explainlikeimfive/comments/1afwzv6/eli5can_anybody_explain_the_birthday_paradox/

https://betterexplained.com/articles/understanding-the-birthday-paradox/

https://www.khanacademy.org/math/statistics-probability/counting-permutations-and-combinations/combinatorics-probability/v/birthday-probability-problem

https://math.stackexchange.com/questions/838440/explain-the-birthday-paradox

https://www.youtube.com/watch%3Fv%3Dm7hI2LulMxE

https://www.scientificamerican.com/article/bring-science-home-probability-birthday-paradox/

https://mathworld.wolfram.com/BirthdayProblem.html

https://statisticsbyjim.com/fun/birthday-problem/