简算 5.04x28 0.96x6.9 3.2x4.6+3.2x5.4 3.82x0.45

简算 5.04x28 0.96x6.9 3.2x4.6+3.2x5.4 3.82x0.45

5.04x28=(5+0.05-0.01)x28=5x28+0.05x28-0.01x28=140+1.4-0.28=141.12
5.04x28=5.04x(30-2)=5.04x30-5.04x2=151.2-10.08=141.12
0.96x6.9=(1-0.04)x(7-0.1)=1x7-0.04x7-1x0.1+0.04x0.1=7-0.28-0.1+0.004=6.624
3.2x4.6+3.2x5.4=3.2x(4.6+5.4)=3.2x10=32
3.82x0.45=3.82x(0.5-0.05)=1.91-0.191=1.719
一些常见的简算数对象“25和4”、“125和8”、“5与任何偶数”以及其他的可以凑整的数。
简便运算是一种高级的混合运算，是混合运算的技巧，学好了简便运算，不仅能提高计算能力、计算速度，更重要的是，使学到的定义、定理、定律、法则、性质、规律等达到融会贯通的境界，是计算题中最能锻炼学生思维能力、开拓学生思路的一种题型。

(5+0.4)*28=5*28+0.4*28=140+11.2=151.2

=5×28+0.04×28=140+1.12=141.12
=（1-0.04）×6.9=6.9-0.276 =6.724
=3.2(4.6+5.4)=32
=4*0.45-0.08*0.45=1.8-0.036=1.764

5.04x28 0.96x6.9 3.2x4.6+3.2x5.4
=(5+0.04)x28 =(1-0.04)x6.9 =3.2x(4.6+5.4)
=5x28+0.04x28 =1x6.9-0.04x6.9 =3.2x10
=140+1.12 =6.9-0.276 =32
=141.12 =6.624

3.82x0.45

=3.82x(0.5-0.05)
=3.82x0.5-3.82x0.05
=1.91-0.191
=1.709