设0.23+0.34=x
0.23+0.34+0.65=y
(1+0.23+0.34)*(0.23+0.34+0.65)-(1+0.23+0.34+0.65)*(0.23+0.34)
=(1+x)y-(1+y)x
=y+xy-x-xy
=y-x
=0.65