× + ÷![]() | ÷[ ×( - )] |
×30+2÷![]() | 201×19.5-19.5 |
+ ×( ÷ ) | 74.6-8.44-1.56. |
(1)
×
+
÷
,=
+
,=
;(2)
÷[
×(
-
)],=
÷[
×
],=
÷
,=2;
(3)
×30+2÷
,=
×30+2×
=
×(30+2),=
×32,=12;
(4)201×19.5-19.5,
=(201-1)×19.5,
=200×19.5,
=3900;
(5)
+
×(
÷
),=
+
×
,=
+
,=
;(6)74.6-8.44-1.56,
=74.6-(8.44+1.56),
=74.6-10,
=64.6.
分析:(1)先算乘法和除法,再算加法;
(2)先算减法,再算乘法,最后算除法;
(3)根据乘法分配律进行计算;
(4)根据乘法分配律进行计算;
(5)先算除法,再算乘法,最后算加法;
(6)根据连减的性质进行计算.
点评:考查了运算定律与简便运算,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律简便计算.