Historians have discovered what may be the world's first decimal point, in an ancient manuscript written 150 years before its next known appearance.
Until now, the earliest known use of a dot as a decimal point was in an astronomical table by the German mathematician Christopher Clavius in 1593. But according to modern scientists, that's a bizarre place to introduce such a massive concept to the world, and Clavius didn’t really go on to use the idea much in his later work. Basically, if he realized the need for the concept and invented a neat way to display and work with it, why didn’t he brag about it?
The answer, it seems, is that Clavius was just borrowing an older idea that had essentially been lost to time, and wasn’t the preferred method in his era. A new study has found that the decimal point dates back to the 1440s - about 150 years earlier - first appearing in the writings of Italian mathematician Giovanni Bianchini.
Bianchini was a professor of mathematics and astronomy at the University of Ferrara, but he also had a background in what we’d now call finance - he was a merchant, and managed assets and investments for a wealthy ruling family of the time. That real-world experience seems to have influenced his mathematical work, since Bianchini was known to have created his own system of dividing measurement units like feet into 10 equal parts to make them easier to work with. Everyone else was using a base-60 system - which is much more challenging than working with multiples of 10.
Now, Dr. Glen Van Brummelen, a professor at Trinity Western University in Canada, has discovered that Bianchini illustrated this system with a decimal point, the first ever. Van Brummelen found that in a manuscript called Tabulae primi mobilis B, Bianchini was using numbers with dots in the middle and showing how to multiply them.
It's perfectly possible that even earlier examples of the decimal point will be found but, for the meantime, Giovanni Bianchini holds the accolade for inventing the decimal dot that changed mathematics forever.