For those of you who are teaching AS ICT on the OCR spec I hope the following spreadsheet I built may be of use.  The spec requires students to know how check digit validation works and they use the example of ISBN-10 numbers.  Irritatingly ISB-10 is no longer the defacto standard for ISBN numbers (ISBN-13 now is) so we are stuck with a system which may not appear on some books.

However I did decide to build the following spreadsheet to demonstrate using formulae how a check digit is calculated.  The benefit is for those who dont want to do the maths in class with their students is that they can enter the first 9 digits of an ISBN-10 number in and they should get the corresponding check-digit spat back out at them.

This was something I cobbled together in about half an hour so I am pretty sure it functions fine – if anyone spots any issues let me know.  I put a nice macro in to clear the numbers so you have to accept that and the file format is therefore Office 2007 macro enabled xls.

cheers

brian