I've seen a lot of compliance tests for credit card processing. These frequently will be Excel sheets with series of test descriptions. For example "Run a $12.45 sale on card number XXXXX with a tax amount of $1.73 and a shipping address of 1234 Main Street, 70242." Inevitably the card numbers are rounded. If you paste in a timestamp for the transaction result, that gets cast weirdly. I end up reworking the default formats for the sheet so that things will not be clobbered.