** Variable vs Constant
**

Variable and constant are two commonly used mathematical concepts. Simply put, a variable is a value that is changing or that have the ability to change. A constant is a value which remains unchanged. Even though the concepts are fundamental in many aspects of mathematics, in elementary levels, it is used in algebra predominantly.

Since the concepts are an integral part of modern mathematics, each and every application of this may include variables and constants in many forms. The concepts have stemmed out into other fields, such as physics and computer science for this reason.

**More about Variable**

In the mathematical context, a variable is a quantity which has a changing or a variable magnitude. Commonly (in algebra), it is represented by an English letter or a Greek letter. It is common practice to call this symbolic letter the variable.

Variables are used in equations, identities, function, and even in geometry. Few of the use of variables are as follows. Variables can be used to represent unknowns in equations such as x^{2}-2x+4=0. It also can represent a rule between two unknown quantities like y=f(x)=x^{3}+4x+9. In probability and statistics, a random variable is a variable that can assume different states or events in the considered set of events. In mathematics, it is customary to emphasize the valid values for the variable, which is called the range. These limitations are deduced from the general properties of the equation or by definition.

Variables are also categorized based on their behaviour. If the variable’s changes are not based on other factors, it is called an independent variable. If the variable’s changes are based on some other variable(s), then it is known as a dependent variable. In statistics, independent and dependent variables are termed as Explanatory variable and Response variable respectively.

The term variable is used in the field of computing too, especially in programming. It refers to a block memory in the program where different values can be stored.

**More about Constant**

In mathematics, a constant is a quantity that does not change its value. Constants are also symbolized by an English or a Greek letter. Usually it represents a real number which has special properties in the context of the problem or the scenario it is used.

It can also be used to represent decimals or irrational numbers of interest, or very large numbers, which are not easily manipulable in a mathematical expression, in its numerical. For example, consider π and e. Avagardro’s constant (L) represents a very large number, which is 6.022 ×10^{23} mol^{-1}.

Constants are often used to represent numbers with physical significance. In physics, chemistry, and any other natural science, you will encounter constants, which are specific letters assigned to represent values of quantities in nature or a mathematical theory. The Universal constant of Gravitation often symbolized by G and Plank’s constant symbolized by h are examples of both the usages. (NB. Planks number is not just a mathematical entity, but it has broad physical interpretations)

**What is the difference between Variables and Constants?**

• Variables are quantities with changing magnitude, hence can assume different values based on the application.

• Constants are quantities with unchanging values, and used to represent numbers with significance.

• Both constants and variables are represented algebraically by English or Greek letters.

• Constants are used to represent quantities in nature which are fixed, and the variables are used to represent unknowns.