Strimko™ is a logic number puzzle invented by The Grabarchuk Family in 2008. It is based on the idea of Latin squares described by a Swiss mathematician and physicist Leonhard Euler (1707-1783) in the 18th century. Strimko challenges were handcrafted by Helen, Tanya, and Peter Grabarchuk, and hundreds of original Strimko puzzles were published in various forms and platforms: Web, iOS, PC/Mac, Kindle, paperback.