(
+
)÷
×(
+
) 6.28+5.74+3.72+5.26
4.27×
+4.73÷8+
(2.3+2.3+2.3+2.3)×2.5.解:(1)(
+
)÷
,=
×
,=
;(2)
×(
+
),=
×
,=
;(3)6.28+5.74+3.72+5.26,
=(6.28+3.72)+(5.74+5.26),
=10+11,
=21;
(4)4.27×
+4.73÷8+
,=4.27×
+4.73×
+
,=(4.27+4.73+1)×
,=10×
,=
;(5)(2.3+2.3+2.3+2.3)×2.5,
=2.3×4×2.5,
=2.3×(4×2.5),
=2.3×10,
=23.
分析:(1)(2)先算括号内的,再算括号外的;
(3)运用加法交换律与结合律简算;
(4)把除法改为乘法,运用乘法分配律简算;
(5)把括号内的算是写成2.3×4,然后运用乘法结合律简算.
点评:此题是考查四则混合运算,掌握运算顺序,仔细观察算式的特点,灵活运用一些定律进行简便计算.