×
+
÷
=________;7.28-3.14+1.72-2.86=________;
(
+
-
)×36=________;[(5-4.75)÷1+2.7]×0.4=________.
311.18分析:(1)先把除法变成乘法,再运用乘法分配律简算;
(2)运用加法结合律,以及连续减去两个数,等于减去这两个数的和简算;
(3)运用乘法分配律简算;
(4)先算小括号里面的减法,再算中括号里面的除法,然后运用乘法分配律简算.
解答:(1)
×
+
÷
,=
×
+
×
,=(
+
)×
,=1×
,=
;(2)7.28-3.14+1.72-2.86,
=(7.28+1.72)-(3.14+2.86),
=9-6,
=3;
(3)(
+
-
)×36,=
×36+
×36-
×36,=3+4-6,
=1;
(4)[(5-4.75)÷1+2.7]×0.4,
=[0.25÷1+2.7]×0.4,
=[0.25+2.7]×0.4,
=0.25×0.4+2.7×0.4,
=0.1+1.08,
=1.18.
故答案为:
,3,1,1.18.点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.