Christopher Columbus is believed to have had two estimates of how far his ship had traveled during the first voyage to the New World. One was a deliberate underestimate to reduce the crew's worries, while the other was his best guess, to be used for practical purposes.

This story is known to be totally false, so please don't repeat it.

However, according Oliver Dunn and James Kelley,[21][22] this was a misunderstanding by Las Casas. Columbus did report two distances each day but one was in measurements he normally used, the other in the Portuguese maritime leagues used by his crew.

I expect most such stories to be just as false as this one. Don't use them unless you really have to.