999 trillion too much for bank’s computers.
While reading The Times this morning, I came across an article that was discussing a numerical problem faced by the banks in Zimbabwe. Now, in case you haven’t heard, Zimbabwe has been suffering from hyperinflation for a while and even everyday items such as bread or beer can cost millions of Zimbabwean dollars.
With even low cost items costing millions of dollars you can imagine that high value transactions, such as those dealt with by banks, can have values of several trillions of dollars. According to this article in The Times, any transaction over 999 Trillion dollars will cause problems with the bank’s computers. The particular problem they have to deal with is called truncation but the article does not go into what truncation actually is.
So what I am wondering is – what is special about 999 trillion (I assume its 999 – the printed value is 9,99 which could mean 999 or 9.99 depending on where you come from)? I guess that it is a limit that was deliberately programmed in for some reason since 999 trillion isn’t anywhere near the usual suspects for numerical overflow.
Any thoughts?
Maybe the programs are using a Binary Coded Decimal (BCD) representation? I think that’s fairly common when dealing with money, to avoid rounding errors.