(100+0.123+0.245+8.9)x(0.123+0.245+8.9+12.71)-(100+0.123+0.245+8.9+12.71)x(0.123+0.245+8.9)
=(100+0.123+0.245+8.9)x(0.123+0.245+8.9）+(100+0.123+0.245+8.9)x12.71-(100+0.123+0.245+8.9)x(0.123+0.245+8.9)-12.71x(0.123+0.245+8.9)
=(100+0.123+0.245+8.9)x12.71-12.71x(0.123+0.245+8.9)
=【(100+0.123+0.245+8.9)-（0.123+0.245+8.9)】x12.71
=【100+0.123+0.245+8.9-0.123-0.245-8.9】x12.71
=100x12.71
=1271