(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.

150₁₀ = (10010110)₂
10010110₂=?
                    
10010110₂ = 226₈

(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.