Worth Data P11/12 - Manual (Page 55)

I-2
The MSI Mod 11 check digit is calculated as follows:
The example bar code data is:
943457842
1. Assign a checking factor to each number, starting with the units position of
the number (in this example, the 2) up to the highest order position (the 9).
Use checking factors of:
2,3,4,5,6,7,2,3,4,5,6,7...
2. Multiply the checking factor with its assigned number and add the products:
4 + 12 + 32 + 35 + 30 + 28 + 6 + 12 + 36 = 195
3. Divide the sum by 11
195/11 = 17 remainder 8
4. Subtract remainder from 11
11 - 8 = 3
5. New Check Digit
3
(If the remainder is 10, no check digit is added.)
6. Data with check digit is:
943457823