题目内容
脱式计算下面各题,怎样简便就怎样算.
5.2×39.8 | 3.8×1.4+6 | 270.4÷(41-28.5)÷0.8. |
分析:(1)把39.8看作40-0.2,运用乘法分配律简算;
(2)先算乘法,再算加法;
(3)先算括号内的,原式变为270.4÷12.5÷0.8,再运用除法的性质简算.
(2)先算乘法,再算加法;
(3)先算括号内的,原式变为270.4÷12.5÷0.8,再运用除法的性质简算.
解答:解:(1)5.2×39.8,
=5.2×(40-0.2),
=5.2×40-5.2×0.2,
=208-1.04,
=206.96;
(2)3.8×1.4+6,
=5.32+6,
=11.32;
(3)270.4÷(41-28.5)÷0.8,
=270.4÷12.5÷0.8,
=270.4÷(12.5×0.8),
=270.4÷10,
=27.04.
=5.2×(40-0.2),
=5.2×40-5.2×0.2,
=208-1.04,
=206.96;
(2)3.8×1.4+6,
=5.32+6,
=11.32;
(3)270.4÷(41-28.5)÷0.8,
=270.4÷12.5÷0.8,
=270.4÷(12.5×0.8),
=270.4÷10,
=27.04.
点评:考查了小数的四则混合运算,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.
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脱式计算下面各题(能简算的要简算)
①(
-
)÷(2-
)
②
+
+
+
+
+
③(
-
)÷
④30.8÷[14-(9.85+1.07)].
①(
11 |
12 |
3 |
4 |
1 |
2 |
②
1 |
1×2 |
1 |
2×3 |
1 |
3×4 |
1 |
4×5 |
1 |
5×6 |
1 |
7×8 |
③(
5 |
7 |
4 |
21 |
5 |
21 |
④30.8÷[14-(9.85+1.07)].
脱式计算下面各题,怎样简便就怎样算.
5.2×39.8 | 3.8×1.4+6 | 270.4÷(41-28.5)÷0.8. |