101*0.87-0.91*27
=(100+1)*0.87-(100-9)*0.27
=87-27+0.87+0.9*2.7
=60+(1-0.13)+(1-0.1)*2.7
=60+1+2.7-0.13-0.27
=60+1+2.7-0.4
=63.3