The exciting story about the origin of the decimal point in mathematics

There is a mathematical tool that we all learned to use in our first classes and continue to use, even without devoting ourselves to anything mathematical professionally or permanently. We're talking about decimal point, That little dot we use in numbers to separate the integer part (integers) from the decimal part (numbers with decimals).

It is used to indicate a change from units to smaller parts of a unit. For example, in 3.14, the decimal point tells us that we have three whole units and 14 hundredths of a unit. It serves as a marker that helps us understand how to read and deal with numbers that are not integers.

Now, have you ever wondered how the decimal point came to be? Who ever thought of wearing it? The first time we saw the decimal point was in a table of sines in a book called “AstrolabiumWritten by Christopher Clavius ​​in 1593. However, it is new investigation It indicates that the decimal point was actually invented about 150 years earlier than previously thought. According to researchers, Clavius's use of fractional notation and the decimal point goes back to the work of Giovanni Bianchini (1440s), whose decimal system was a hallmark of his calculations in astronomy.

Bianchini was a 15th-century Italian astronomer, mathematician, and humanist. He was born in 1410 in Ferrara, Italy, and died in 1469. He was famous for his contributions to the field of astronomy and his studies of the works of Ptolemy, the ancient Greek astronomer. Bianchini also excelled in translating and commenting on classical works, which contributed to the study and preservation of ancient knowledge during the Italian Renaissance. Now, because it's the front of the decimal point.

The story the researchers tell is fascinating: At some point, around the 1520s and 1530s, the young Giovanni Bianchini worked as a Venetian merchant, which provided him with the necessary training in subjects such as commercial arithmetic and algebra.

It is likely that during the 1530s the d'Este family, which ruled the Duchy of Ferrara (a region in northern Italy), appointed Bianchini to act as administrator of their estates, where his mathematical skills could be put to good use. Almost all of Bianchini's known works written in this period are astronomical, perhaps partly to meet the astronomical needs of the Este court, but due to his work with the d'Este family he was also forced to create his own decimal chart. By studying a treatise written by Bianchini in the 1540s, called Tabulae primi mobilis B, the authors discovered that Bianchini not only had a decimal number system, but also had a decimal point like the one we use today.

“I realized that he uses this just like we use it, and he knows how to do the math,” Glen van Brummelen, a historian of mathematics at Trinity Western University in Langley, Canada, and an author on the study, told Nature. “I remember running through the halls of my dorm with my computer trying to find anyone who was awake, shouting ‘Look at this, this guy is doing decimal points in 1440!’”