Octal is a system of real numbers that was commonly used in older computing systems. The main use of the octal system today is in Unix applications. It's digits range from 0 to 7. The decimal system is the main number system used today. It has nine discrete digits ranging from 0 to 9. The main purpose of octal and the more popular hexadecimal system is because they are easier to convert to and from binary than can be done by the decimal system.
- Count the number of digits
Starting from the right, count the number of digits beginning with the number 0. The number 427 would be numbered 210.
- Multiply each digit by 8 to a power
The next step is to multiply each individual digit by 8 to the power of that digit's place in the number. For example, if you want to convert the number 427 base 8 to decimal, you will arrange the conversion like so: (4 * 8^2) + (2 * 8^1) + (7 * 8^0).
- Add the products of each digit
The next step is to multiply each individual digit and then add the products together: 256 + 16 + 7 = (279)base 10. Thus, the answer would be the decimal number 279.