(5-(1/5))*5(5-(1/5))*55*(5-(1/5))5*(5-(1/5))(5-(1/5))*5(5-(1/5))*55*(5-(1/5))5*(5-(1/5))(5-(1/5))*5(5-(1/5))*55*(5-(1/5))5*(5-(1/5))
用三个5和一个1算起来等于245×（5-1÷5）=24
5的平方+5-5-1=24
