Arithmetic operators in Javascript - Mini Project: Build & Apply

Arithmetic Operators Practice

📖 Scenario: You are helping a small shop calculate prices and discounts for their products. You will use arithmetic operators to do simple math calculations.

🎯 Goal: Build a small program that calculates the total price of items, applies a discount, and shows the final amount to pay.

📋 What You'll Learn

Create variables with exact values for product prices

Create a variable for discount percentage

Calculate total price and discounted price using arithmetic operators

Print the final price after discount

💡 Why This Matters

🌍 Real World

Calculating prices and discounts is common in shops and online stores to show customers how much they pay.

💼 Career

Understanding arithmetic operators is essential for any programming job that involves calculations, such as web development, data analysis, or game programming.

1

Create product price variables

Create three variables called price1, price2, and price3 with values 10, 20, and 30 respectively.

Javascript

// Create variables price1, price2, and price3 with values 10, 20, and 30
// Your code here

Hint

Use let to create variables and assign the exact numbers.

2

Create discount percentage variable

Create a variable called discountPercent and set it to 10 to represent a 10% discount.

Javascript

let price1 = 10;
let price2 = 20;
let price3 = 30;
// Create variable discountPercent with value 10
// Your code here

Hint

Remember to use let and assign the number 10.

3

Calculate total and discounted price

Create a variable called totalPrice that adds price1, price2, and price3. Then create a variable called discountedPrice that subtracts the discount amount from totalPrice. Use arithmetic operators to calculate the discount amount as totalPrice * discountPercent / 100.

Javascript

let price1 = 10;
let price2 = 20;
let price3 = 30;
let discountPercent = 10;
// Calculate totalPrice by adding price1, price2, and price3
// Calculate discountedPrice by subtracting discount from totalPrice
// Your code here

Hint

Use + to add prices and -, *, and / to calculate the discount.

4

Print the final discounted price

Write a console.log statement to print the text "Final price after discount: " followed by the value of discountedPrice.

Javascript

let price1 = 10;
let price2 = 20;
let price3 = 30;
let discountPercent = 10;
let totalPrice = price1 + price2 + price3;
let discountedPrice = totalPrice - (totalPrice * discountPercent / 100);
// Print the final discounted price
// Your code here

Hint

Use console.log and string concatenation with +.

Practice

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

easy

A. %

B. /

C. **

D. *

Solution

1. Step 1: Understand the remainder operator

   The operator % returns the remainder after division of two numbers.

2. Step 2: Compare with other operators

   / is division, ** is power, and * is multiplication, so they don't give remainder.

3. Final Answer:

   % -> Option A

4. Quick Check:

   Remainder operator = % [OK]

Hint: Remainder operator looks like a percent sign % [OK]

Common Mistakes:

• Confusing division / with remainder %
• Using * or ** instead of %
• Thinking + or - can give remainder

2. Which of the following is the correct syntax to calculate 5 to the power of 3 in JavaScript?

easy

A. 5 ** 3

B. 5 ^^ 3

C. 5 ^ 3

D. pow(5, 3)

Solution

1. Step 1: Identify the power operator in JavaScript

   JavaScript uses ** to calculate powers, like 5 ** 3 means 5 to the power 3.

2. Step 2: Check other options for correctness

   ^ is bitwise XOR, ^^ is invalid syntax, and pow() is not a built-in function in JavaScript.

3. Final Answer:

   5 ** 3 -> Option A

4. Quick Check:

   Power operator = ** [OK]

Hint: Use ** for power, not ^ or pow() [OK]

Common Mistakes:

• Using ^ instead of ** for power
• Trying to use pow() like in other languages
• Typing invalid operators like ^^

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

console.log(10 % 4);

medium

A. 6

B. 0

C. 2

D. 4

Solution

1. Step 1: Calculate 10 divided by 4

   10 divided by 4 is 2 with a remainder of 2.

2. Step 2: Understand the % operator

   The % operator returns the remainder, so 10 % 4 equals 2.

3. Final Answer:

   2 -> Option C

4. Quick Check:

   10 % 4 = 2 [OK]

Hint: Remainder is what's left after division [OK]

Common Mistakes:

• Confusing remainder with quotient
• Thinking % does division
• Choosing 0 or 4 as remainder incorrectly

4. Find the error in this code snippet:

let result = 5 **;
console.log(result);

medium

A. console.log syntax error

B. Using wrong operator for power

C. Variable name 'result' is invalid

D. Missing right operand for ** operator

Solution

1. Step 1: Check the power operator usage

   The power operator ** needs two operands, like 5 ** 2. Here, the right operand is missing.

2. Step 2: Verify other parts of the code

   The variable name and console.log syntax are correct, so no errors there.

3. Final Answer:

   Missing right operand for ** operator -> Option D

4. Quick Check:

   Power operator needs two numbers [OK]

Hint: Power operator needs number on both sides [OK]

Common Mistakes:

• Leaving out the second number after **
• Thinking variable names cause error here
• Assuming console.log is wrong

5. You want to split 100 candies equally among 6 kids and find how many candies remain undistributed. Which expression gives the number of leftover candies?

hard

A. 100 / 6

B. 100 % 6

C. 100 - 6

D. 100 ** 6

Solution

1. Step 1: Understand the problem

   We want the leftover candies after dividing 100 by 6, which means the remainder.

2. Step 2: Choose the correct operator

   The remainder operator % gives the leftover amount, so 100 % 6 is correct.

3. Final Answer:

   100 % 6 -> Option B

4. Quick Check:

   Leftover = total % number [OK]

Hint: Use % to find leftovers after division [OK]

Common Mistakes:

• Using / which gives quotient, not remainder
• Subtracting numbers directly instead of remainder
• Using power operator mistakenly