巧算(1+0.23+0.34)*(0.23+0.34+0.65)-(1+0.23+0.34+0.65)*(0.23+0.34)
问题描述:
巧算(1+0.23+0.34)*(0.23+0.34+0.65)-(1+0.23+0.34+0.65)*(0.23+0.34)
答
设:A=0.23+0.34
B=0.23+0.34+0.65
原式=(1+A)XB-(1+B)XA
=B+AB-A-AB
=B-A
=(0.23+0.34+0.65)-(0.23+0.34)
=0.65