You need to set an 8-digit PIN. There is a hexadecimal keypad (0-9, A-F), but there are some restrictions on the PIN you can choose. You can re-use digits but you cannot have repeating digits next to each other, e.g. the PIN cannot contain "00", "222", "77", "BB", "CCC", etc. You cannot have adjacent digits next to each other, e.g. the PIN cannot contain "34", "67", "21","9A", "DC", etc. (0 and F are considered adjacent for this restriction; think of the 16 digits as being in a circle) 1. How many possible PINs are there? 2. How many bits of entropy does a PIN contain? If rounding is required, answer to 1 decimal point. 3. Why is this an approximation and not a true reflection of the strength of a PIN, despite the restrictions in place?