题目内容
计算下面各题.(能简算要简算)
(1)25.4×1.25×0.8;
(2)3.9÷2×(4.94-3.64);
(3)38.4÷0.25÷4;
(4)3.47÷(3.47×4 );
(5)213.6÷0.8÷0.3;
(6)6.6÷5.5×1.7;
(7)32.8×10.5÷0.6;
(8)42÷(5.25÷0.25).
(1)25.4×1.25×0.8;
(2)3.9÷2×(4.94-3.64);
(3)38.4÷0.25÷4;
(4)3.47÷(3.47×4 );
(5)213.6÷0.8÷0.3;
(6)6.6÷5.5×1.7;
(7)32.8×10.5÷0.6;
(8)42÷(5.25÷0.25).
考点:小数四则混合运算,运算定律与简便运算
专题:运算顺序及法则,运算定律及简算
分析:(1)运用乘法交换律简算;
(2)先算小括号里面的减法,再算括号外的除法,最后算括号外的乘法;
(3)(4)运用除法的性质简算;
(5)(6)(7)按照从左到右的顺序计算;
(8)先算小括号里面的除法,再算括号外的除法.
(2)先算小括号里面的减法,再算括号外的除法,最后算括号外的乘法;
(3)(4)运用除法的性质简算;
(5)(6)(7)按照从左到右的顺序计算;
(8)先算小括号里面的除法,再算括号外的除法.
解答:
解:(1)25.4×1.25×0.8
=25.4×(1.25×0.8)
=25.4×1
=25.4;
(2)3.9÷2×(4.94-3.64)
=3.9÷2×1.3
=1.95×1.3
=2.535;
(3)38.4÷0.25÷4
=38.4÷(0.25×4)
=38.4÷1
=38.4;
(4)3.47÷(3.47×4 )
=3.47÷3.47÷4
=1÷4
=0.25;
(5)213.6÷0.8÷0.3
=267÷0.3
=890;
(6)6.6÷5.5×1.7
=1.2×1.7
=2.04;
(7)32.8×10.5÷0.6
=344.4÷0.6
=574;
(8)42÷(5.25÷0.25)
=42÷21
=2.
=25.4×(1.25×0.8)
=25.4×1
=25.4;
(2)3.9÷2×(4.94-3.64)
=3.9÷2×1.3
=1.95×1.3
=2.535;
(3)38.4÷0.25÷4
=38.4÷(0.25×4)
=38.4÷1
=38.4;
(4)3.47÷(3.47×4 )
=3.47÷3.47÷4
=1÷4
=0.25;
(5)213.6÷0.8÷0.3
=267÷0.3
=890;
(6)6.6÷5.5×1.7
=1.2×1.7
=2.04;
(7)32.8×10.5÷0.6
=344.4÷0.6
=574;
(8)42÷(5.25÷0.25)
=42÷21
=2.
点评:本题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定律进行简便计算.
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