А)110010011_{2}=1*2^8+1*2^7+0*2^6+0*2^5+1*2^4+0*2^3+0*2^2+1*2^1+1^2^0=
=256+128+16+2+1=403_{10}
б)101010101_{2}=1*2^8+0*2^7+1*2^6+0*2^5+1*2^4+0*2^3+1*2^2+0*2^1+1^2^0=
=256+64+16+4+1=341_{10}
в)1010101001_{2}=1*2^9+0*2^8+1*2^7+0*2^6+1*2^5++0*2^4+1*2^3+0*2^2+0*2^1+1*2^0=
=512+128+32+8+1=681_{10}