Listen

$1$:$21$:$28$ remaining

A bank wants to reject erroneous account numbers to avoid invalid input.

Management of the bank was told that there is a method that involves adding another numbers to an algorithm to compaccount numbers and subjecting the other numbers to and are with the extra numbers. What technique is this?

$53$ Optical character recognition $($OCR$)$ sobvare.

Self$-$checking number.

Validity check.

Field $($format$)$ check.