In mathematical reasoning it is often necessary to make statements about objectsthat are represented by letters called variables. For example, if the variable xis used to stand for a number in some problem, we might be interested in thestatement “x is a prime number.” Although we may sometimes use a singleletter, say P, to stand for this statement, at other times we will revise thisnotation slightly and write P(x), to stress that this is a statement about x.The latter notation makes it easy to talk about substituting some number forx in the statement. For example, P(7) would represent the statement “7 is aprime number,” and P(a + b) would mean “a + b is a prime number.” If astatement contains more than one variable, our abbreviation for the statementwill include a list of all the variables involved. For example, we might representthe statement “p is divisible by q” by D( p, q). In this case, D(12, 4) wouldmean “12 is divisible by 4.”Although you have probably seen variables used most often to stand fornumbers, they can stand for anything at all. For example, we could let M(x)stand for the statement “x is a man,” and W (x) for “x is a woman.” In thiscase, we are using the variable x to stand for a person. A statement might evencontain several variables that stand for different kinds of objects. For example,in the statement “x has y children,” the variable x stands for a person, and ystands for a number.Statements involving variables can be combined using connectives, just likestatements without variables.Example 1.3.1. Analyze the logical forms of the following statements:1. x is a prime number, and either y or z is divisible by x.2. x is a man and y is a woman and x likes y, but y doesn’t like x

Which of the following describes a variable? A. the part of an expression that includes parentheses B. a letter or symbol that represents a value that never changes C. a letter or symbol that represents an unknown quantity D. the part of an expression that always remains the same

What is a variable in programming and why are they used?

A letter that stands for a number in an expression or an equation is called a

A variable is a name given to a memory location to store some value. Since the memory location can store different values during execution of a program, the name used to refer to it, is called a variable.Since variables are a part of identifiers, they follow the same naming conventions. Like identifiers, a valid variable name can start with an alphabet or an underscore ( _ ) and later have a combination of one or more letters, digits and underscores.A few examples of valid variable names are : sum,total,average_marks, etc.When creating a variable, we should mention the type of data (for example, integer or character) that it would store. This is called the data type of that variable.In a C program, variables should be declared before their usage.The format for declaring a variable is data_type variable_name;.For example:int count; // int is the data type and count is the variable nameThe above declaration can also be combined with initialisation. In such a case, the format for declaring a variable is data_type variable_name = constant_value;.We shall learn more about data types and constants in the later sections.Given below is an example of declaring and initialising a variable in the same line:int count = 9; // Here the variable count is being initialised to a constant value 9 Invalid#include <stdio.h>void main() { printf("age : %d", age); int age = 34; // this is the declaration statement} Valid#include <stdio.h>void main() { int age = 34; printf("age : %d", age);}Select the correct statements from the given statements.Variable is an identifier which is used to store data.The value stored in a variable is fixed. It cannot be changed once it is initialised to a value.Variable is the name given to a memory location.The type of data stored in a variable is specified by its data types.

Programmers generally choose names for their variables that are meaningful and document what the variable is used for.Question 10Select one:TrueFalse