Octal Numbers  Decimal Number 

Octal numbers are made up of 8 distinct symbols or digits from 0 to 7 ( 0, 1, 2, 3, 4, 5, 6, 7).  Decimal numbers are made up of 10 distinct symbols or digits ranging from 0 to 9 (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). 
The radix for octal number is 8 i.e all the digits in an octal number are expressed as powers of 8.  The radix for decimal number is 10 i.e all the digits or values in a decimal number are expressed as of powers of 10. 
Example of octal number : 7777 ( Equivalent to four thousand ninety five in decimal )  Example of Decimal number : 4095 ( Four thousand ninety five) 
Applications of octal numbers
 Applications of decimal numbers
