题目内容
递等式计算,写出必要的计算过程,能简便计算的用简便方法计算:
(1)7.06×2.4-5.7
(2)5.4×99+5.4
(3)9.6×72+9.6×28
(4)(1.25×2.5)×4
(5)10.4+72×0.81
(6)11×0.6×0.4
(7)(12.8+4.99)÷0.2
(8)1.25×8+2.5×4.4.
解:(1)7.06×2.4-5.7,
=16.944-5.7,
=11.244;
(2)5.4×99+5.4,
=5.4×(99+1),
=5.4×100,
=540;
(3)9.6×72+9.6×28,
=9.6×(72+28),
=9.6×100,
=960;
(4)(1.25×2.5)×4,
=1.25×(2.5×4),
=1.25×10,
=12.5;
(5)10.4+72×0.81,
=10.4+58.32,
=68.72;
(6)11×0.6×0.4,
=6.6×0.4,
=2.64;
(7)(12.8+4.99)÷0.2,
=17.79÷0.2,
=88.95;
(8)1.25×8+2.5×4.4,
=10+2.5×0.4×11,
=10+11,
=21.
分析:(1)、(5)、(6)、(7)、(8)按照有括号的先算括号里面的,没有括号时先算乘除法,后算加减法的顺序计算;
(2)、(3)运用乘法分配律进行简算得解;
(4)运用乘法结合律简算得解.
点评:此题考查小数四则混合运算与简便计算,完成本题要注意分析式中数据,运用合适的简便方法计算.
=16.944-5.7,
=11.244;
(2)5.4×99+5.4,
=5.4×(99+1),
=5.4×100,
=540;
(3)9.6×72+9.6×28,
=9.6×(72+28),
=9.6×100,
=960;
(4)(1.25×2.5)×4,
=1.25×(2.5×4),
=1.25×10,
=12.5;
(5)10.4+72×0.81,
=10.4+58.32,
=68.72;
(6)11×0.6×0.4,
=6.6×0.4,
=2.64;
(7)(12.8+4.99)÷0.2,
=17.79÷0.2,
=88.95;
(8)1.25×8+2.5×4.4,
=10+2.5×0.4×11,
=10+11,
=21.
分析:(1)、(5)、(6)、(7)、(8)按照有括号的先算括号里面的,没有括号时先算乘除法,后算加减法的顺序计算;
(2)、(3)运用乘法分配律进行简算得解;
(4)运用乘法结合律简算得解.
点评:此题考查小数四则混合运算与简便计算,完成本题要注意分析式中数据,运用合适的简便方法计算.
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