题目内容
8.综合计算、能简算的要简算28.4×99+28.4
0.25×3.2×1.25
201×0.47-0.47
2.415÷2.3×2.04
0.8×1.2÷0.8×1.2
3.4×4.9+66×0.49.
分析 (1)(3)(6)运用乘法分配律简算;
(2)在计算时,把3.2看作4×0.8,运用乘法结合律简算;
(4)从左往右依次计算;
(5)调整运算顺序,使计算简便.
解答 解:(1)28.4×99+28.4
=28.4×(99+1)
=28.4×100
=2840
(2)0.25×3.2×1.25
=0.25×4×(0.8×1.25)
=1×1
=1
(3)201×0.47-0.47
=0.47×(201-1)
=0.47×200
=94
(4)2.415÷2.3×2.04
=1.05×2.04
=2.142
(5)0.8×1.2÷0.8×1.2
=(0.8÷0.8)×(1.2×1.2)
=1×1.44
=1.44
(6)3.4×4.9+66×0.49
=34×0.49+66×0.49
=(34+66)×0.49
=100×0.49
=49
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定律简便计算.
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