The Chinese or Romans?
Certainly not the Romans.
The concept of decimal fractions was known to the Chinese in the first century BCE (Joseph Needham, Science and Civilisation in China) but in Europe the modern decimal notation originates from the Dutch mathematician Simon Stevin (1548/49 - 1620) although the decimal point comes later and was in use by the time of John Napier.
greek
The number IS in decimal notation!
3.88 is decimal notation.
It is already in decimal notation as 4.8
300 is already in decimal notation.
greek
The operations are the same as in decimal (+ - / x) the positional notation is somewhat different.
The decimal numeral system (also called base ten or occasionally denary) has ten as its base. Decimal notation often refers to a base-10 positional notation.
Two: "0" and "1." Digital (as opposed to analogue) computers all use binary arithmetic/notation, which is positional like decimal arithmetic/notation, but employs only two tokens (0, 1) in place of decimal's ten (0 .. 9). The term "bit" for the smallest unit of information, incidentally, is a contraction of the phrase "binary digit."
3.88 is decimal notation.
The number IS in decimal notation!
Sigma notation was invented, not discovered.Sigma notation was invented, not discovered.Sigma notation was invented, not discovered.Sigma notation was invented, not discovered.
decimal notation of 335 = 335.0
42.4 as decimal notation = 42.4
300 is already in decimal notation.
decimal notation of 3.159 = 3.159
It is already in decimal notation as 4.8