A domino computer built by Matt Parker and his team in 2014. Matt Parker is an Australian mathematician and stand-up comedian based in London. He is also the Public Engagement in Mathematics Fellow at Queen Mary University of London. Matt set out to build, in his words, “the world’s slowest computer” that could sum up two numbers, each between zero and seven, using just dominoes. He and his team successfully used the giant domino computer to work out the sum of four and six. A day later, they extended the domino computer to work out the sum of two numbers between zero and 15. This required building a much bigger circuit using 10,000 dominoes! The photo shows this second, bigger, domino computer. You may watch how the second attempt fared on the following Youtube link: https://www.youtube.com/watch?v=OpLU__bhu2w