Measurement unit

The myth of a short Napoleon partly stems from measurement unit confusion. His 168 cm was 5 pieds 2 pouces in French units, which the British misread as 5 feet 2 inches (158 cm). He was actually taller than the average French man of his era at 164 cm.

In 1999, NASA lost a $327.6 million Mars probe to a measurement unit mix-up. Lockheed Martin sent data in pound-force seconds; NASA entered it into a newton-second program without converting. The orbiter drifted off course and burned up in Mars's atmosphere.

Columbus's discovery of America resulted from a measurement unit mix-up. He confused Arab miles with Roman miles, vastly underestimating Earth's size. People mocked his voyage not because they thought Earth was flat—they knew it was round—but because his math was clearly wrong.