注：代表分号,/代表除号,21表示二分之一,5+41=541表示5又4/1（带分数）56*5=654*2=5/821*4=2445*2=2/531*5=3/572*6=7/1252*6=5/1235*2=3/1057*2=5/1456*1=5/679*2=7/1854*2=5/8245*...