Arithmetic operand must be number TypeScript

Why This Happens

In TypeScript, you used a non-number in an arithmetic expression. This is one of the most common TypeScript errors developers encounter. Understanding the root cause helps you fix it quickly and prevent it from recurring.

The Problem

const x = '5' * 2;

The Fix

const x = Number('5') * 2;

Step-by-Step Fix

1. 1

   Identify the error

   Look at the error message: TS2363: Right side of arithmetic must be number. This tells you exactly what went wrong.

2. 2

   Find the cause

   Check the stack trace to find which line of your TypeScript code triggered this error.

3. 3

   Apply the fix

   Use the corrected code pattern shown above. Test to confirm the error is resolved.