$```$

TEST$\_$ACC$\_$NUM$\_$A $=[1,9,4,5,5,7,2]$

SAMPLE$\_$MATRIX$\_$A $=[$

$[3,4,5],$

$[8,8,8],$

$[1,0,5],$

$[1,8,7]$

$]$

SAMPLE$\_$MATRIX$\_$A$\_$T $=[$

$[3,8,1,1],$

$[4,8,0,8],$

$[5,8,5,7],$

$]$

SAMPLE$\_$MATRIX$\_$B $=[$

$[3,4,5,2,9,1,5,3,2,8],$

$[8,8,8,9,2,7,8,7,3,5],$

$[1,0,5,2,4,9,4,0,3,8],$

$[1,8,7,5,6,2,4,9,7,1],$

$[6,3,3,8,7,3,3,2,2,9],$

$[0,2,4,5,1,9,4,2,8,5],$

$[9,6,7,0,2,4,1,0,2,1],$

$[1,5,9,0,2,4,2,2,4,6],$

$[5,5,4,9,3,1,2,3,4,0],$

$[2,6,7,9,9,5,3,8,2,2]$

$]$

##################################################################

### PART $1$ : Account Numbers

#############################################################

def sum$\_$of$\_$digits$($number: int$)->$ int:

$\text{'}\text{'}\text{'}$

TODO: This function is provided as a potential helper function.

It is not marked and you do not need to implement it$.$

If you decide to not complete it$,$ remove it completely.

Given a non$-$negative integer 'number', return the sum of all its digits.

Preconditions: number $>=0$

$>>>$ sum$\_$of$\_$digits$(1234)$

$10$

$>>>$ sum$\_$of$\_$digits$(8888)$

$32$

$```$