18427(10) = 1000111111111011(2)
So, it will need 16 bits (16 digits from the binary value) for 18427 itself. For the complement (the sign), add 1 more bit: the answer is 17.
6
It depends on the expression.
The number of bits required to represent an integer number depends on the size of the integer, there is no absolute answer. Generally speaking, a binary number made up of some number of bits can be considered to directly represent an integer number according to the rules of binary arithmetic. If you specify the question a little differently you can come up with a question that does have an absolute answer. For example, if you ask what range of integers can be represented by a binary number with N bits, the answer is exactly 0 to 2^N (ignoring alternate ways to characterize binary numbers such as signed two's complement). More specifically, an 8 bit binary number can represent the integers from 0 to 255. There is also another way to restate your original question. That would be to assume that you are asking how many bits (at a minimum) does it take to represent a particular integer. In that case, again assuming unsigned binary arithmetic, the answer would be found by determining the next higher power of two than the number in question and finding log base 2 of that number. For example, the minimum number of bits required to represent the integer 60 would be 6, where the next higher power of two than 60 is 64, and the log base 2 (simply the power to which 2 must be raised to arrive at the number) is 6. In theory, an infinite number of bits could represent an infinity of integers, but that is probably not really what you are asking.
103
If there are N discs, the minimum number of moves required is 2N - 1.
8
9 bits
17 bits would allow a value up to 131071.
The same number of bits are used to represent 1's complement and 2's complement. To take 2's complement, first take the 1's complement, then add 1 to the result.
127.
The minimum number of tables is 3.
The minimum number of tables is 3.
two
in 2's Complement there is only one zero: All zeros In 1's Complement there are two zeros: All zeros, and All ones ("negative" zero). So you have one less signed number you can represent with the same amount of bits. For example, with 8 bits, with 2's Complement you can represent -128 to +127 while with 1's complement you can only represent -127 to +127.
Eight.
the minimum number ICs required for 8085 to start working properly are 3
3