Question

19.7*5.3+4.7*19.3这道题怎样用简便方法

Answer 1

19。7x5.3+4.7x19.3=19.7x(5+0.3)+(5-0.3)x(19.7-0.3)=19.7x5+19.7x0.3+5x19.7-5x0.3-19.7x0.3+0.3x0.3=10x19.7+(19.7-5-19.7+0.3)x0.3=197-4.7x0.3

Answer 2

19.7*5.3+4.7*19.3=(19.3+0.4)*5.3+4.7*19.3=19.3(5.3+4.7)+0.4*5.3=195.12或者
19.7*5.3+4.7*19.3=19.7*5.3+4.7*(19.7-0.4)=19.7(5.3+4.7)-0.4*4.7=195.12
这种类型尽量提取公约数，好计算的就可以

Answer 3

(20-0.3)x(5+0.3)+(5-0.3)x(19+0.3)
=20x5+20x0.3-0.3x5-0.3x0.3+5x19+5x0.3-0.3x19-0.3x0.3
=(20+19)x5+(20-5-0.3+5-19-0.3)x0.3
=39x5+0.4x0.3
=195+0.12
=195.12