Business tax exam question regarding share disposals

Hi

I recently took the business tax exam and I think I may have incorrectly answered a question with regards to share disposal's for a company. I added shares purchased within the previous 9 days to the share pool and then worked out the cost of all shares as part of the calculation. I now know this was the wrong thing to do. Are the examiners harsh when marking tasks as I believe my method was correct in answering the question with the exception of incorrectly adding the shares purchased within the previous 9 days. Do the emaniners still credit marks for workings etc or do they fail the entire task as a result of this minor error?

Thanks

Alex