题目内容
14.脱式计算(能简算的要用简算)4.2×7.8+2.2×4.2 | 9.5×101 | (8×3.82)×1.25 |
0.125×72 | 0.6×3.9×0.8 | 42×0.39+4.2×6.1 |
分析 (1)(2)根据乘法分配律简便计算;
(3)根据乘法交换律和结合律简便计算;
(4)变形为0.125×8×9简便计算;
(5)从左往右依次计算;
(6)先变形为42×0.39+42×0.61,再根据乘法分配律简便计算.
解答 解:(1)4.2×7.8+2.2×4.2
=4.2×(7.8+2.2 )
=4.2×10
=42
(2)9.5×101
=9.5×(100+1)
=9.5×100+9.5
=950+9.5
=959.5
(3)(8×3.82)×1.25
=(8×1.25)×3.82
=10×3.82
=38.2
(4)0.125×72
=0.125×8×9
=1×9
=9
(5)0.6×3.9×0.8
=2.34×0.8
=1.872
(6)42×0.39+4.2×6.1
=42×0.39+42×0.61
=42×(0.39+0.61)
=42×1
=42
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.
练习册系列答案
相关题目
9.直接写得数.
17%+35%= | 1÷50%= | 0.6+40%= | $\frac{5}{8}$+37.5%= |
$\frac{4}{5}$÷20%= | $\frac{2}{5}$÷$\frac{1}{6}$= | $\frac{2}{3}$×40%= | $\frac{3}{5}$×25%= |