Q.What is the meaning of a%b? Find the value of 21%4.

Arithmetic operators carry out the basic mathematical operations in C. There are five of them:

• + addition, - subtraction, * multiplication, / division, and
• % the modulus (remainder) operator, which gives the remainder of an integer division.

An arithmetic expression is formed by joining variables and constants with these operators, for example y = 3*x*x + 4*x - 2;, which is the C form of $y = 3x^2 + 4x - 2$. Note that C has no power symbol, so $x^2$ is written as x*x, and multiplication must be written explicitly with *.

Two rules matter when evaluating arithmetic:

1. Integer division truncates. When both operands are integers, / discards the fractional part, so 25/6 gives 4, not 4.166. To get a real result, at least one operand must be real (e.g. sum/4.0). …