5= 1 个零10 = 2 个零15 = 3个零20 = 4个零25 = 5个零30 = 6个零35 = 7个零40 = 8个零45 = 9个零50 = 10个零如此 我们得到个结论 1+2...+n = (n+1)n/2=255解得：n=50 （负根舍去）50*5=25 0 是最小的所以250+5-1=254...