Creating a Mod 43 Check Digit Calculator in Excel
1. Enter the number you want to calculate the Mod 43 Check Digit for in a cell.
2. In the cell next to the number, enter the following formula:
Formula:
=MOD(43-MOD(SUMPRODUCT(--MID(A1,ROW(INDIRECT("1:"&LEN(A1))),1)*{43,41,37,31,29,23,19,17,13,7,5,3}),43),43)
- Break down the number into individual digits using the MID function.
- Multiply each digit by a corresponding weight from the Mod 43 Check Digit algorithm.
- Sum the weighted digits using the SUMPRODUCT function.
- Subtract the result from 43 and take the remainder using the MOD function.
- Subtract the result from 43 again to get the Mod 43 Check Digit.
3. Press enter and the Mod 43 Check Digit for the number will be displayed in the cell.