Відповідь:
101011(2) = 1*2^5+1*2^3+1*2^1+1*2^0 = 32+8+2+1 = 43(10)
125(8) = 1*8^2+2*8^1+5*8^0 = 64+16+5 = 85(10)
D7(16) = D(13)*16^1+7*16^0 = 208+7 = 215(10)
261(8) = 010(2)110(6)001(1) = 010110001(2)
C3B5(16) = 1100(C=12)0011(3)1011(B=11)0101(5) = 1100001110110101(2)
