Arithmetic operators in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add two numbers and print the result.

PHP

<?php
$a = 5;
$b = 3;
$result = $a [1] $b;
echo $result;
?>

Drag options to blanks, or click blank then click option'

A/

B-

C+

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using minus - instead of plus +.

The plus sign + adds two numbers together.

2fill in blank

medium

Complete the code to multiply two numbers and print the result.

PHP

<?php
$x = 7;
$y = 4;
$product = $x [1] $y;
echo $product;
?>

Drag options to blanks, or click blank then click option'

A*

B-

C+

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using plus + instead of multiplication *.

The asterisk * multiplies two numbers.

3fill in blank

hard

Fix the error in the code to correctly divide two numbers and print the result.

PHP

<?php
$num1 = 10;
$num2 = 2;
$division = $num1 [1] $num2;
echo $division;
?>

Drag options to blanks, or click blank then click option'

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using minus - or multiplication * instead of division /.

The forward slash / divides one number by another.

4fill in blank

hard

Fill both blanks to create a dictionary of squares for numbers greater than 3.

PHP

<?php
$numbers = [1, 2, 3, 4, 5];
$squares = [];
foreach ($numbers as $num) {
    if ($num [1] 3) {
        $squares[$num] = $num [2] 2;
    }
}
print_r($squares);
?>

Drag options to blanks, or click blank then click option'

A>

B<

C**

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using less than < instead of greater than >.

Using multiplication * instead of power ** for squaring.

The operator > checks if a number is greater than 3. The operator ** raises the number to the power of 2 (square).

5fill in blank

hard

Fill all three blanks to create an array of numbers and filter those divisible by 2.

PHP

<?php
$numbers = range(1, 10);
$evens = [];
foreach ($numbers as [1]) {
    if ([2] % 2 [3] 0) {
        $evens[] = [2];
    }
}
print_r($evens);
?>

Drag options to blanks, or click blank then click option'

A$num

Bnum

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using variable without $ sign.

Using not equal != instead of equal ==.

The variable $num is used to loop through numbers. The operator == checks if the remainder is zero, meaning the number is divisible by 2.

Practice

1. Which arithmetic operator in PHP is used to find the remainder of a division?

easy

A. The subtraction operator (-)

B. The modulus operator (%)

C. The multiplication operator (*)

D. The division operator (/)

Solution

1. Step 1: Understand the modulus operator and compare with other operators

   The modulus operator (%) returns the remainder after division of two numbers. Division (/) returns the quotient, multiplication (*) multiplies, and subtraction (-) subtracts.

2. Final Answer:

   The modulus operator (%) -> Option B

3. Quick Check:

   Remainder = % [OK]

Hint: Remainder means modulus (%) operator [OK]

Common Mistakes:

• Confusing division (/) with modulus (%)
• Using multiplication (*) instead of modulus
• Thinking subtraction (-) gives remainder

2. Which of the following is the correct syntax to add two variables $a and $b in PHP?

easy

A. $sum = $a / $b;

B. $sum = $a - $b;

C. $sum = $a * $b;

D. $sum = $a + $b;

Solution

1. Step 1: Identify the addition operator and check the syntax correctness

   In PHP, the plus sign (+) adds two numbers or variables. The syntax $sum = $a + $b; correctly assigns the sum of $a and $b to $sum.

2. Final Answer:

   $sum = $a + $b; -> Option D

3. Quick Check:

   Addition uses + [OK]

Hint: Use + for addition between variables [OK]

Common Mistakes:

• Using - instead of + for addition
• Using * or / which are multiplication/division
• Missing semicolon at end

3. What will be the output of the following PHP code?

$x = 10;
$y = 3;
echo $x % $y;

medium

A. 1

B. 3

C. 0

D. Syntax Error

Solution

1. Step 1: Calculate the modulus of 10 and 3 and understand the output of echo $x % $y;

   10 divided by 3 is 3 with a remainder of 1. The modulus operator (%) returns the remainder, so output is 1.

2. Final Answer:

   1 -> Option A

3. Quick Check:

   10 % 3 = 1 [OK]

Hint: Modulus gives remainder, 10 % 3 = 1 [OK]

Common Mistakes:

• Confusing modulus with division result
• Expecting 3 instead of remainder 1
• Syntax errors from missing semicolon

4. Identify the error in this PHP code snippet:

$a = 5;
$b = 0;
echo $a / $b;

medium

A. Incorrect use of multiplication operator

B. Syntax error due to missing semicolon

C. Division by zero error

D. No error, outputs 0

Solution

1. Step 1: Analyze the division operation and check for syntax correctness

   Dividing any number by zero is not allowed and causes an error in PHP. Semicolons are present; multiplication operator is not used here.

2. Final Answer:

   Division by zero error -> Option C

3. Quick Check:

   Division by zero causes error [OK]

Hint: Never divide by zero to avoid errors [OK]

Common Mistakes:

• Ignoring division by zero error
• Thinking output is 0
• Confusing syntax error with runtime error

5. You want to calculate the total cost after applying a 15% discount on a price stored in $price. Which PHP expression correctly calculates the discounted price?

hard

A. $discounted = $price - ($price * 0.15);

B. $discounted = $price + ($price * 0.15);

C. $discounted = $price * 0.15;

D. $discounted = $price / 0.15;

Solution

1. Step 1: Calculate the discount amount and subtract discount from original price

   Multiply the price by 0.15 to get 15% of the price. Subtract the discount amount from the original price to get the discounted price.

2. Final Answer:

   $discounted = $price - ($price * 0.15); -> Option A

3. Quick Check:

   Discounted price = price - 15% price [OK]

Hint: Subtract 15% of price for discount [OK]

Common Mistakes:

• Adding discount instead of subtracting
• Using only 15% value without subtracting
• Dividing price by 0.15 incorrectly