Which type of number system is represented by base 8?
Octal
Octal is base 8 and uses digits 0–7. Binary, decimal and hexadecimal have bases 2, 10 and 16 respectively.
If 1 is added to each odd digit and 2 is subtracted from each even digit in the number 8317456, what will be the sum of the digits that are second from the left and second from the right?