Khalil Klouche reinvents the calculator with his tremendous Knock Knock

Since the days of GCSE maths I haven’t had much cause to use a calculator but my solar-powered Casio will always have a place in my heart. But there’s a new pretender to the throne in the form of this extraordinary Knock Knock offering from Swiss designer Khalil Klouche. Designed for small children, it works through an Arduino circuit board and presents an amazingly tactile, fun way to engage youngsters with fundamental maths. Well I say fundamental, you may find yourself having to concentrate on these simple sums more than you’d expect!