1.(498*381+382)/(498*382-116)=(498*382-498+382)/(498*382-116)=1
2.分子,分母各提取1665和1998后可得：1665(1+11+111.)/1998(1+11+111...)=1665/1998
3.题目可是下式,LZ：
（1+1/8+1/9）*(1/8+1/9+1/10)-(1+1/8+1/9+1/10)*(1/8+1/9)
=（1+1/8+1/9）*(1/8+1/9+1/10)-(1+1/8+1/9)*(1/8+1/9)-(1/10)*(1/8+1/9)
=（1+1/8+1/9）*(1/10)-(1/10)*(1/8+1/9)
=1/10