111011.11=2^5+2^4+2^3+2^1+2^0+2^(-1)+2^(-2)
=32+16+8+2+1+0.5+0.25
=59.75
10101.101=2^4 + 1*2^2 + 1*2^0 + 1*2^-1 + 1*2^-3
=16 + 4 + 1 + 0.5 + 0.125
=21.625
(111011.11)2+(10101.101)2=81.375 =(1010001.011)2