A. What is the meaning of check digit
Check digits are decimals number (or
alphanumeric character) added to the end of many numbers such as an account
number for purpose of detecting the sorts of errors made on data entry.
two different example where check digits are used.
digits can be used to verify bank routing codes, credit card numbers, ISBN
numbers on books, magnetic stripe cards, Postnet and Intelligent Mail barcodes that
used by the United States Postal Service, vehicle identification numbers, and etc.
You do not realize that check digits are very important in our lives.
Here are some dates of birth that are to
be entered into an ICT system:
be valid dates of birth because of dd/mm/yyyy we still in 2018. If the person
born in 3010 it means that he/she born in the future
be valid dates of birth because of dd/mm/yyyy format we do not have 13 months.
We only have 12 months each year
be valid dates of birth because of dd/mm/yyyy format we do not have 30 days in
the second months. In February we only have 28 or 29 days
L is letter and N is number, we can use format checks
are given an annual salary, we can use
“Data can be valid yet still be incorrect”.
For example date of birth: 11/13/2017, it means the data still incorrect and
you can still correct the date by changing the months. We do not have 13 months,
we can change it to 12 or other months.
a. Presence check means we need to fill some database,
while others can be left empty. A presence check would check to make sure that
data had been entered into a field.
field that needs presence check is student score note. If we do not fill the
score the note field does not appear, the note field will still blank. The field
that does not need presence check is code for a car. We need to fill all the
field so we do not need the presence field.
A. Using questionnaires
Examination of existing documentation.
The correct list:
3). Development and testing
Development and testing
A. Using direct changeover can simply stop
using the old system one day and start using the new system the next day.
the advantage using direct changeover, fastest method of implementation,
benefits are available immediately.
disadvantages using direct changeover, if the new system fails, you might lose
all the data.