Question

What is the check digit for a Visa number 4536-6336-3663-777d?

Answer 1

To find the check digit you follow the next steps:

The number is:

4536-3636-3663-777d

1. You Double every other number as follow:

2. You Sum digits and write the number as follow: (If you have for ex. 10 the sum of its digits is 1+0= 1)

3. Then you get the sum of all the digits in the third row:

$4+1+3+3+6+3+3+3+3+3+6+6+7+5+7=63$

4. to get the value of the d you:

- take the result of the part 3: (63)

- Take the units part of that result: (3)

- substract the units from 10

10 - 3= 7

Then the check digit is that one: 7

Then the final number is:

4536636363636637777