24×( + - ) | ÷[( + )× ] | 375+450÷18×25 | 2.5×1.25×32. |
+
-
),=24×
+24×
-24×
,=6+3-4,
=9-4,
=5;
(2)
÷[(
+
)×
],=
÷[
×
],=
÷
,=4;
(3)375+450÷18×25,
=375+25×25,
=375+625,
=1000;
(4)2.5×1.25×32,
=2.5×1.25×(4×8),
=(2.5×4)×(1.25×8),
=10×10,
=100.
分析:(1)根据乘法分配律进行简算;
(2)先算小括号里面的加法,再算中括号里面的乘法,最后算除法;
(3)先算除法,再算乘法,最后算加法;
(4)把32拆成4×8,然后再根据乘法交换律和结合律进行简算.
点评:四则运算,先弄清运算顺序,然后再进一步计算即可,能简算的要简算.