Paxar Monarch 9413 - Manual (Page 87)

3. Next, the digits of the products are added together. Two-digit
products are treated as two separate digits.
This is the sum of the digits.
2 + 0 + 2 + 6 + 6 + 1 + 6 + 5 + 4 + 3 + 3 + 6 = 44
4. Divide the sum of the digits by the modulus (10 in this case),
only to the whole number. The balance is called the
remainder.
4
10 44
40
4
5. Subtract the remainder from the modulus.
The result becomes the check digit. In this case, the check
digit is 6.
10 - 4 = 6
Defining Field Options 5-17