One of my first jobs as a teenager was not software related, but basically just accounting support. A mid-size retail chain had acquired another retailer and needed help going over the books. This was in the 90s and I was basically typing stuff in an Excel sheet and getting a sum. Last day on the job I gave them the bottom-line number of something (revenue?) and my manager looked at it and said it seemed way off. Whatever, I'm done for the summer. Few weeks later there's a story that the company they acquired had lied about their value by a large margin and it was enough to put them out of business forever. Close all their stores and liquidated. I know it was not my fault at all, but I like to think it was my Excel sheet that destroyed them.