The notation system supports presenting the largest numbers using fewest digits is
Hexadecimal.
Explanation:
The hexadecimal numeral system, often shortened to "hex", is a numeral system made up of 16 symbols (base 16).
Each Hex digit can store 16 bits of information. A single decimal digit stores 4 bits while binary obviously stores 1 bit.
Each hexadecimal digit represents four binary digits, also known as a nibble, which is half a byte.
The main reason why we use hexadecimal numbers is because it is much easier to express binary number representations in hex than it is in any other base number system.
The standard numeral system is called decimal (base 10) and uses ten symbols: 0,1,2,3,4,5,6,7,8,9. Hexadecimal uses the decimal numbers and six extra symbols.
B. Change the router's default administrative password
Explanation:
The best way to prevent any unauthorized use is to change the password to something more secure using 12 minimum characters and including number, symbols, upper and lower case.