Represents 8 types of digits from 0 to 7, so the base of number system is 8. It takes exactly three binary digits to represent an octal digit. Similar to binary number system, it is also positional system and has two parts i.e. integer and fractional part separated by radix point (.).
Octal to Binary conversion
(2351.23)8 = ( 010 011 101 001 . 010 011 )2 = (010011101001.010011)2
Octal to Decimal conversion
Octal to Hexadecimal conversion
As it was difficult to handle binary number system, it gave rise to two more number system i.e octal and hexadecimal.