BCD is the binary coded decimal form of representation of numbers in 4 bits.E.g. The BCD representation of 5 is 0101. BCD representation of 22 is 00100010.

The Roman number system isn’t a positional number system since it uses symbols to represent numbers.
The octal number system uses digits from 0-7, the binary number system uses digits from 0-1 whereas, the hexadecimal number system uses digits from 0-15.

 To get the binary equivalent of any number, we need to divide the number by 2 and obtain the remainders as :
computer-fundamentals-questions-answers-binary-number-system-q3
We then write the remainders in the reverse order as 1010 .

 The octal equivalent is obtained by grouping the numbers into three, from right to left before decimal and from right to left after the decimal place.
Here,
computer-fundamentals-questions-answers-binary-number-system-q5
i.e. 145.12 is the octal equivalent of the number.

In hexadecimal number system, 1110 = 15, which is represented by the alphabet E.
Some representations are:
A 10
B 11
C 12
D 13
E 14
F 15.