分析:(1)先把除法变成乘法,再运用乘法分配律简算;
(2)先算小括号里面的减法,再算中括号里面的减法,最后算括号外的除法;
(3)先把62.5×0.48根据积不变规律变成6.25×4.8,再运用乘法分配律简算;
(4)先算小括号里面的加法,再算括号外的除法;
(5)运用凑整法简算;
(6)把
分解成1-
,再运用乘法分配律简算.
解答:解:(1)
(-)÷,
=(
-
)×
,
=
×
-
×
,
=
-
,
=
;
(2)
[1-(-)]÷13,
=[1-
]÷13,
=
÷13,
=
;
(3)3.75×4.8+62.5×0.48,
=3.75×4.8+6.25×4.8,
=(3.75+6.25)×4.8,
=10×4.8,
=48;
(4)
÷(
+
),
=
÷,
=
;
(5)1991+199.1+19.91+1.991,
=(2000-9)+(200-0.9)+(20-0.09)+(2-0.009),
=(2000+200+20+2)-(9+0.9+0.09+0.009),
=2222-9.999,
=2222-(10-0.001),
=2222-10+0.001,
=2212.001;
(6)
×37,
=(1-
)×37,
=1×37-
×37,
=37-
,
=36
.
点评:本题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.