There are two math problems that have been shrouded in dust for a hundred years: female students in a boarding school 15 have to go out for a walk in groups of three every day. How to arrange for each student to walk in groups of three with other 14 students once a week? 1850, the British mathematician Kirkman put forward the above problem, and this seemingly simple mathematical problem could not be solved by anyone during 130 years! It has become one of the 100 world problems recognized by the international mathematics community. Old people in Shanghai have been dealing with toys for nearly half a century, which is not round and has nothing to do with mathematics. In the first half of 200 1 2000, he happened to see the introduction of Kirkman's puzzle in a science pictorial and was immediately attracted. "This is a math problem that arranges and combines roads. I specially designed a set of toys that can definitely solve it! "

Fang Buhui specially designed a jigsaw puzzle of "Girls' Walking Timetable": a small box with 7 squares, representing 7 days a week; Divide the girls who walk in groups of three into five groups vertically with five squares, and each square represents one group. The girls in each box are very active. You can put them in or take them out to combine with other girls. It took Fang Buyuan only two hours to miraculously spell out the first song "Walking Arrangement" on the platter. What's even more incredible is that Fang Buyuan designed more than 530 combinations of threesomes for 15 girls through this "walking course".