Arithmetic operators in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP code using arithmetic operators?

Consider the following PHP code snippet. What will it output when run?

PHP

<?php
$a = 10;
$b = 3;
echo $a % $b;
?>

A 3

B SyntaxError

C 0

D 1

💡 Hint

The % operator gives the remainder of division.

The expression 10 % 3 calculates the remainder when 10 is divided by 3, which is 1.

❓ Predict Output

intermediate

What is the output of this PHP code with mixed arithmetic?

What will this PHP code print?

PHP

<?php
$x = 5;
$y = 2;
$result = $x ** $y + $x / $y;
echo $result;
?>

A 12.5

B 27

C 27.5

D SyntaxError

💡 Hint

Remember operator precedence: exponentiation before division and addition.

5 ** 2 = 25, 5 / 2 = 2.5, 25 + 2.5 = 27.5.

❓ Predict Output

advanced

What is the output of this PHP code with increment operators?

What will this PHP code output?

PHP

<?php
$a = 3;
$b = $a++ + ++$a;
echo $b;
?>

A 8

B 7

C 6

D SyntaxError

💡 Hint

Remember post-increment returns the value before increment, pre-increment increments first.

Initially, $a=3. $a++ returns 3 then $a becomes 4. ++$a increments $a to 5 then returns 5. So sum is 3 + 5 = 8.

❓ Predict Output

advanced

What error does this PHP code produce?

What error will this PHP code raise when executed?

PHP

<?php
$x = 10 / 0;
echo $x;
?>

A DivisionByZeroError

B Warning: Division by zero

C Fatal error: Uncaught Exception

D No error, outputs 0

💡 Hint

Division by zero is not allowed in PHP 7+ and throws an error.

In PHP 7 and later, dividing by zero throws a DivisionByZeroError exception.

🧠 Conceptual

expert

How many items are in the resulting array after this PHP code runs?

What is the number of elements in the array $arr after running this code?

PHP

<?php
$arr = [];
for ($i = 0; $i < 5; $i++) {
    $arr[$i] = $i * 2;
}
$arr[5] = $arr[2] + $arr[4];
unset($arr[1]);
?>

A 6

B 5

C 4

D 7

💡 Hint

Count elements after adding and removing keys.

Initially 5 elements (keys 0 to 4). Then key 5 is added (total 6). Then key 1 is removed (total 5).