Arithmetic operators
- Node.js course
- Beginner
- Lesson 24/116
- 4 min
Learn basic arithmetic with +, -, *, / and %.
Arithmetic operators
In JavaScript, arithmetic operators perform basic math on numbers: + (addition), - (subtraction), * (multiplication), / (division) and % (modulo, remainder).
For example, 10 + 3 returns 13, 10 / 3 returns 3.333..., 10 % 3 returns 1. Modulo gives the remainder after division; very useful for odd/even checks.
These operators also work with variables: price * qty.
Modulo and exponent
The modulo operator is written with % and gives the remainder after division. For example, 7 % 3 returns 1 (7 = 2*3 + 1).
This is ideal for checking whether a number is odd or even: n % 2 === 0 means even, n % 2 === 1 means odd.
For exponentiation, use **: 2 ** 3 returns 8. In old code you may see Math.pow(2, 3).
Practice Arithmetic calculation
Declare a = 10 and b = 3. Compute sum, product and remainder as a + b, a * b, a % b respectively. Print each with console.log.
Starter code
const a = 10;
const b = 3;
// Compute sum, product, remainder variables
// Log all three with console.logSample solution
const a = 10;
const b = 3;
const sum = a + b;
const product = a * b;
const remainder = a % b;
console.log(sum);
console.log(product);
console.log(remainder);Expected output
13 30 1
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does 7 % 3 return?
- 10
- 2.33
- 0
- 1 Correct answer
Explanation: 7 = 2*3 + 1, remainder is 1.
2 Addition example
const sum = 10 ____ 5;const sum = 10 + 5;Explanation: is subtraction, * is multiplication, / is division.
3 Match the operators
| Term | Meaning |
|---|---|
+ |
Addition |
- |
Subtraction |
* |
Multiplication |
% |
Modulo (remainder) |