How to Use Arithmetic Operators in PHP: Simple Guide

In PHP, you use +, -, *, /, and % to perform addition, subtraction, multiplication, division, and modulus operations respectively. These operators work between numbers to calculate and return a result.

Syntax

Arithmetic operators in PHP are used between two numbers (operands) to perform calculations. The common operators are:

• + for addition
• - for subtraction
• * for multiplication
• / for division
• % for modulus (remainder)

Example syntax: $result = $a + $b; adds two variables.

php

<?php
$a = 10;
$b = 3;
$sum = $a + $b;  // adds 10 and 3
$difference = $a - $b;  // subtracts 3 from 10
$product = $a * $b;  // multiplies 10 by 3
$quotient = $a / $b;  // divides 10 by 3
$remainder = $a % $b;  // remainder of 10 divided by 3
?>

Example

This example shows how to use arithmetic operators to calculate and print results of basic math operations.

php

<?php
$a = 15;
$b = 4;

echo "Addition: " . ($a + $b) . "\n";
echo "Subtraction: " . ($a - $b) . "\n";
echo "Multiplication: " . ($a * $b) . "\n";
echo "Division: " . ($a / $b) . "\n";
echo "Modulus: " . ($a % $b) . "\n";
?>

Output

Addition: 19
Subtraction: 11
Multiplication: 60
Division: 3.75
Modulus: 3

Common Pitfalls

Common mistakes include dividing by zero, which causes errors, and misunderstanding the modulus operator which returns the remainder, not the quotient.

Also, using arithmetic operators on non-numeric strings can lead to unexpected results or warnings.

php

<?php
// Wrong: division by zero causes error
// $result = 10 / 0; // Warning: Division by zero

// Right: check divisor before dividing
$divisor = 0;
if ($divisor != 0) {
    $result = 10 / $divisor;
} else {
    $result = 'Cannot divide by zero';
}
echo $result;
?>

Output

Cannot divide by zero

Quick Reference

Operator	Description	Example	Result
+	Addition	5 + 3	8
-	Subtraction	5 - 3	2
*	Multiplication	5 * 3	15
/	Division	5 / 2	2.5
%	Modulus (remainder)	5 % 2	1

Key Takeaways

Use +, -, *, /, and % to perform basic math operations in PHP.

Always check for division by zero to avoid errors.

Modulus (%) returns the remainder after division, not the quotient.

Arithmetic operators work best with numeric values to avoid unexpected results.

Use parentheses to control operation order when combining multiple operators.