用简便方法计算下面各题.(1)7.86+9.73+2.14+0.27 (2)216.45-(4.5+1.45) (3)(

(1)7.86+9.73+2.14+0.27
=（7.86+2.14）+（9.73+0.27）
=10+10
=20
(2)216.45-(4.5+1.45)
=216.45-1.45-4.5
=215-4.5
=210.5
(3)(1/13X1/18)X13X18
=18*13
=（20-2）*13
=260-26
=234
(4)999X778+333X666
=999*（778+222）
=999000
(6)9又1/3+99又1/3+999又1/3+2
=（9+99+999）+（1/3 *3)+2
=1110-3+3
=1110 .