Question #$2$: to$\_$decimal$($oct$\_$num$)10$ pts

Given a number oct$\_$num in octal system $($base $8),$ return oct$\_$num in decimal system $($base $10).$ In

the octal number system, each digit represents a power of eight and it uses the digits $1$ to $7.$ To

convert a number represented in octal system to a number represented in decimal system, each

digit must be multiplied by the appropriate power of eight. For example, given the octal number

$2068$ results in the decimal number $13410$:

$206$

$828180$

$$ You are NOT allowed to type convert num to a string $,$ use lists in any form, add

the digits into a list to traverse or process the number, or to use of the math module

Preconditions and Postconditions

oct$\_$num: int $->$ Positive number that always starts with a digit in range $1-7$

Returns: int $->$ decimal representation of oct$\_$num