Arithmetic Operators in C
Arithmetic operators are used to perform mathematical calculations in a program. Various arithmetic operators in C language are as follows:
 + [Addition Operator]
 – [Subtraction Operator]
 * [Multiplication Operator]
 / [Division Operator]
 % [Modulus Operator]
1. +
Addition operator is represented as plus (+) sign. It is used to add values of numeric variables, constants and expressions.
Example
10 + 3 = 13
2. –
Subtraction operator is represented as a hyphen (). It is used to subtract value of one numeric quantity from another.
The quantity may be a variable, constant or expression.
Example
10 – 3 = 7
3. *
Multiplication operator is represented as an asterisk (*). It is used to multiply value of one numeric quantity with another numeric quantity.
Example
10 * 3 = 30
4. /
Division operator is represented as a forward slash (/). It is used to divide value of one numeric quantity by another numeric quantity.
Example
10 / 3 = 3
5. %
Modulus operator is represented as a percent sign(%). It returns remainder after dividing one numeric quantity by another numeric quantity. The quantity may be a variable, constant or expression.
Example :
10 % 3 =1
Program to demonstrate arithmetic operators.  Output (Line Wise) 
#include<stdio.h> int main() { int a=10; 

printf(“\nEnter value of a=”); scanf(“%d”,&a);  Enter value of a=10 
printf(“\nEnter value of b=”); scanf(“%d”,&b);  Enter value of b=3 
c=a+b; printf(“\na+b=%d”,c);  a+b=13 
c=ab; printf(“\nab=%d”,c);  ab=7 
c=a*b; printf(“\na*b=%d”,c);  a*b=30 
c=a/b; printf(“\na/b=%d”,c);  a/b=3 
c=a%b; printf(“\na%%b=%d”,c);  a%b=1 
getch(); return (0); } 
Write C programs for following:
 The basic salary of an employee is typed through the keyboard. DA is 45% of basic salary, and HRA is 10% of basic salary. Write a program to calculate his net salary calculated as basic salary+DA+HRA
 Write a program to find the total marks and percentage of a student from five subjects. The marks of five subjects should be entered through the keyboard.
 Write a program to interchange the values of two variables.
 Write a program to find the circumference of a circle calculated as 2πr.
Write output of following
1.
main()
{
printf(“%d”,(10/3));
}
2.
main()
{
int a=20;
printf(“%f”,(10/3));
printf(“%d”,(a%3));
}
3.
main()
{
int z=2*5+2*8;
printf(“%d”,z);
}
4.
main()
{
int a = 10;
float b = 6;
printf ( “%f” , a / b ) ;
}
5.
main()
{
int j;
j= 10*50% 3/2;
printf ( “%d” ,j) ;
}