1 1 0 1 0 1
-   1 0 1 1 1 1
____________
    0  0 0 1 1 0
____________

    1 1 0 1 0 1
+  1 0 1 1 1 1
   __________
    11 0 0 1 0 0
   __________

(i) Binary Coded Decimal is mostly used in simple electronic devices like calculators and microwaves.
(ii) This is because it makes it easier to process and display individual numbers on their Liquid Crystal Display (LCD) screens.

The common coding schemes are ;
(i) Binary Coded Decimal (BCD),
(ii) Extended Binary Coded Decimal Interchange Code (EBCDIC).
(iii) American Standard Code for. Information Interchange (ASCII).
(iv) Unicode

(i) MSB (Most Significant Bit) - The leftmost bit carries the largest weight and hence, is called the MSB.
(ii) LSB (Least Significant Bit) - The rightmost bit carries the smallest weight and hence, is called the LSB.
(iii) Binary Point - It is used to separate the integer and fractional part of the binary number, Eg. (1011.011)₂

(i) The octal number system is playing a vital role in digital computer work.
(ii) The octal number system has a base of 8: It means that it has eight unique symbols such as 0,1 ,2,3,4,5,6 and 7.
(iii) Thus, each digit of an octal number can have any value from 0 to 7

(a) -22₁₀ + 15₁₀

                                                  (1111)₂ \(\Rightarrow\) (00001111)₂
(10110)₂ \(\Rightarrow\)(00010110)₂


20₁₀ + 25₁₀ = 00101101₂

(i) ISCII is the system of handling the character of Indian local languages. This as a 8-bit coding system.
(ii) Therefore it can handle 256 (28) characters. This system is formulated by the department of Electronics in India in the year 1986-88 and recognized by Bureau of Indian Standards (BIS).
(iii) Now this coding system is integrated with Unicode.

(i) There are only two digits in the Binary system, namely, 0 and 1.
The numbers in the binary system are represented to the base 2 and the positional multipliers are the powers of 2.
(ii) The left most bit in the binary number is called as the Most Significant Bit (MSB) and it has the largest positional weight.
(iii) The right most bit is the Least Significant Bit (LSB) and has the smallest positional weight.

A numbering system is a way of representing numbers. Each number system is uniquely identified by its base value or radix. Radix or base is the count of number of digits in each number system. Radix or base is the general idea behind positional numbering system.
Example:
Binary Number System - Radix 2
Octal Number Systenm - Radix 8
Decimal Number System - Radix 10
Hexadecimal Number System - Radix 16.