You may know of the bank clerk who, every time he has to transfer money from one account to another, rounds it down to the nearest cent and accumulates the leftover amounts in his account. The fractions are tiny, but they add up over millions of transactions, and eventually he has enough to buy a palace in Rio, or whatever your fancy is. Here are two stories about salami slicing, posted to the Microsoft Excel Developers List Excel-L, and the European Spreadsheet Risks Interest Group List.
Randy Harmelink pointed out some nice legends about salami slicing in Snopes and NetworkWorld. Apparently, it played a rôle in the plot of Superman III; but I liked best Wikipedia's remark about that man for whom the words "shamefaced" and "skulk" were coined:
Woody Allen joked that as a young man he stole a loaf of bread one slice at a time from a bakery at which he worked. After a crisis of conscience, he broke into the bakery to try to return the loaf but was caught red-handed.
Here's the first story, from Darryl Collins:
I have an example for you when I worked at ExxonMobil Australia and they couldn't get the product reco for the Asia Pacific islands to balance. I was asked to check out the problem and fix it.
Turns out the issue was that all the spreadsheets were set up to round the transactions (measured in barrels) to millions. Many of the smaller islands would only take 230,000 barrels, which would show up in Excel as Zero when rounded.
Now this wasn't a problem until some of the users started to print out these spreadsheets, and give them to someone else to key into SAP rather than loading the data automatically.
Naturally the autoload worked fine as the underlying value was sent to SAP, but when they printed them out, the print-out would say 0 (zero) so that is what was entered into SAP. Hmmm...
You don't have to do that for too long before you lose an oil tanker or two worth of oil.
And from an earlier time, Steve Ball reminisced:
Many years ago I formed an internal audit department for Mark C. Bloom Company. They were an auto tire and repair chain (eventually bought by Goodyear). We simply could not figure why each of the 67 stores seemed to have anywhere from $2,000 to $8,000 per month missing from cash flow, based on the sales figures. This was before computerized POS registers, and each store had between one and 4 calculators at the work stations in the repair bays. The calculators were used to add up the repair bills and to calculate sales tax.
One of my auditors, totally by accident, noticed that the calculator in a repair bay of the store he was at was set to round down. He moved the switch to 5/4 and checked the other two calculators, which were also set to round down.
To make a long story short, we discovered that virtually every calculator in every store was rounding down. The way the keyboard was set up, the saran wrap that covered the keys to protect them from oil and grease, and the ham-fingered hands of the mechanics moving from the keys to rip off the paper tape, insured that all the buttons were set to round down.
The result, over hundreds or thousands of transactions, was rounding losses on the sales tax calculations of $2,000 to $8,000 every month.
The fix? We taped the damned keys in the 5/4 place with duct tape.