JavaScript - Arithmetic Operators

Overview

Estimated time: 15–25 minutes

Perform math using arithmetic operators. Be mindful of floating-point precision and BigInt rules.

Learning Objectives

• Use arithmetic operators with Number and BigInt.
• Understand prefix vs postfix increment.

Prerequisites

• JavaScript - Operators Overview

Examples

2 + 3      // 5
7 - 4      // 3
6 * 7      // 42
7 / 2      // 3.5
7 % 2      // 1
2 ** 3     // 8

let x = 1;
let y = x++; // y = 1, x = 2 (postfix)
let z = ++x; // x = 3, z = 3 (prefix)

Precision

0.1 + 0.2 === 0.3 // false (floating point rounding)

BigInt

10n + 20n // 30n
// 10n + 1  // TypeError: Cannot mix BigInt and other types

Common Pitfalls

• Relying on exact floating-point sums; format or round if needed.
• Mixing BigInt and Number in the same expression throws.

Exercises

1. Compute compound interest and discuss formatting the result to 2 decimals.
2. Rewrite an expression to use ** instead of Math.pow.