Patrick Vennebush shared this puzzle https://mathjokes4mathyfolks.wordpress.com/2020/10/27/covering-100-squares/, wondering how many ways there are to cover a 10x10 square with whole length squares.[br][br]1 10x10 square and 100 1x1 squares, but which in between? 1 9x9 and 19 1x1, so 20 squares is possible. Which numbers of squares are impossible?[br][br]Use the reset in the top right corner to tidy up and try a different configuration.