# Breaking Down the Basics: What Isn't a Positional Number System?

One of the fundamental topics in mathematics is understanding different number systems. These systems provide us with different ways of writing and manipulating numbers. One type of number system, which is a common topic in introductory math classes, is the **positional number system**. But which of the following is not a positional number system?

## What is a Positional Number System?

In its simplest form, a positional number system is a way of representing numbers in terms of place value. This means that the value of a digit in a number is determined by its position in the number. For example, in the number 15, the "1" is in the "tens" place and the "5" is in the "ones" place. As such, the number 15 is actually equal to 10 + 5, or "1" in the tens place and "5" in the ones place.

Positional number systems are used in almost every day applications, from keeping track of money to calculating the time of day. They are also used in more advanced applications such as computer programming, cryptography, and mathematics.

## Examples of Positional Number Systems

There are several different types of positional number systems. The most common type is the base-10 system, otherwise known as the decimal system. This system uses 10 digits (0-9) to represent all numbers. For example, in the number 15, the "1" is in the tens place and the "5" is in the ones place. Other examples of positional number systems include the base-2 system (binary system) and the base-16 system (hexadecimal system).

## Which of the Following is Not a Positional Number System?

The answer is the Roman numeral system. Unlike the decimal system, which uses place value to represent numbers, the Roman numeral system uses a set of symbols to represent numbers. For example, the number 15 is represented as "XV" in the Roman numeral system. Each symbol has a specific value, and the value of the number is determined by the sum of the individual values of the symbols. While the Roman numeral system is an important part of mathematics, it is not a positional number system.

## Conclusion

The positional number system is a fundamental and important concept in mathematics. It is used in everyday applications such as counting money and keeping track of time, as well as more advanced applications such as computer programming and cryptography. The most common type of positional number system is the base-10 system, also known as the decimal system. Other examples of positional number systems include the base-2 system and the base-16 system. The answer to the question "which of the following is not a positional number system?" is the Roman numeral system.