| ①1.43×60%-0.6×0.43 | ② ×14 | ③0.125+ -( - ) |
④ -(0.75+ ) | ⑤99.8÷12.5÷24 | ⑥[1-(75%+ )]÷0.25. |
=1.43×0.6-0.6×0.43,
=0.6×(1.43-0.43),
=0.6×1,
=0.6;
②
×14,=
×(13+1),=
×13+
,=11+
,=11
;③0.125+
-(
-
),=
+
-(
-
),=
+
-
+
,=(
+
)+(
-
),=1+3,
=4;
④
-(0.75+
),=2.75-0.75-0.9,
=2-0.9,
=1.1;
⑤99.8÷12.5÷24,
=99.8÷(12.5×24),
=99.8÷(12.5×8×3),
=99.8÷300,
=
;⑥[1-(75%+
)]÷0.25,=[1-(
+
)]÷
,=[1-
]×4,=-
×4,=-
.分析:①把百分比数化为小数,运用乘法分配律简算;
②把14看作13+1,运用乘法分配律简算;
③运用加法的性质以及加法交换律与结合律简算;
④运用加法的性质以及加法结合律简算;
⑤运用除法的性质,改写成99.8÷(12.5×24),再把24看作8×3,计算即可;
⑥把百分数和小数化为分数,先算小括号内的,再算中括号内的,最后算括号外的.
点评: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律简便计算.