45.08−4.5+8.238−8.2=45+0.08−45×0.1+8.238−8.2=（45×1−45×0.1)+0.08+（8.238−8.2）=45×（1−0.1）+0.08+（8.238−8.2）=45×0.9+0.08+0.038=40.5+0.08+0.038=40.618
