(1+0.12+0.34)x(0.12+0.34+0.56)-(1+0.12+0.34+0.56)x(0.12+0.34)
=(0.34+0.56+0.12+0.34)x(0.12+0.34+0.56)-(1+0.12+0.34+0.56)x(0.12+0.34+0.56-0.56)
=0.34x(0.12+0.34+0.56)+(0.56+0.12+0.34)x(0.12+0.34+0.56)-(0.12+0.34)
-(0.12+0.34+0.56)x(0.12+0.34+0.56)+0.56x(0.12+0.34+0.56)
合并同类项,约去相同的式子
=（0.34+0.56）x（0.12+0.34+0.56）-0.12-0.34
=（0.12+0.34+0.56）-0.12-0.34
=0.56