[math-fun] Whopper math problems

Burger King offers a free Whopper (hamburger) to students who solve this math problem (and also download the Burger King surveillance app^H^H^Hmalware): -sum((-1)^j*((5!*5)/(4!))^(1/2),j,1,461) (all of you can solve this w/o a computer or even a pencil) Perhaps one of you can convince Burger King's advertising agency (Paris-based "Buzzman") to sneak some real math problems into this promotion? https://www.adweek.com/creativity/burger-king-lets-students-unlock-free-whop... BTW, what high-school-level math problems would be fun for this sort of promotion?