They were invented in India and brought to Europe by Arabs.
Use of a new calendar system
.
The Islamic Empire, they also invented checks. _____ The previous answer is not true. By the time of Hammurabi's Code, dating to around 1760 BCE, banking was well enough developed to justify laws governing banking operations. This predates the Islamic empire by almost 2400 years.
The Romans.
Gupta mathematicians developed the concept of zero in the use of math, and also developed the decimal system based on the number 10. They also created a number writing system that was later adopted by the Islamic Empire. This system became known as Arabic Numerals, but is really a Gupta achievement.
Roman numerals were developed by the Etruscans who once ruled the Romans. Little in history is known about these strange and mysterious people, the Etruscans, were known in ancient times as the people of the sea. The way we write out Roman numerals today is different in the way that the Romans themselves actually did because today's rules governing the Roman numeral system were introduced during the Middle Ages and that was centuries after the fall of the Roman Empire.
Roman numerals were created by the Etruscans who once had a powerful influence over the Romans.
Numerical system of the Roman Empire
They were developed using a Roman system that worked out for pretty much all of the Romans
The Roman numeral system was used during ancient Roman times, but use of the system continued long after the Roman empire declined. In the 14th century, Roman numerals were slowly replaced by Hindu-Arabic numbers.
It was the Etruscans who first conceived this form of numeracy system and the Etruscans once ruled the Romans. Little is known in history about the mysterious Etruscans who once lived in the part of Italy that today is called Tuscany.
Many historians believe that the number system using Arabic numerals, now used throughout most of the world, was developed during the Gupta dynasty along with the base 10 decimal system and the concept of zero.
The Hindus developed the Hindu numeral system. Hindus are Indians.
The feudal system developed during the Zhou dynasty.
Arabian
Im not entirely sure but it is most likely Sumerians(If you need more help just type "Sumerian Accomplishments" in Google or something), they invented either a form of the number system or the real number system we use today. This is my homework question and the choices for answers are aryan empire, Persian empire, mauryan empire, or gupta empire.