LeetCode - 150 - Multiply Strings

Wed, 17 Jun 2026 08:13:55 +0300

The problem

Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string.

Note: You must not use any built-in BigInteger library or convert the inputs to integers directly.

Example 1:

Input: num1 = "2", num2 = "3"
Output: "6"

Example 2:

Input: num1 = "123", num2 = "456"
Output: "56088"

Constraints:

1 <= num1.length, num2.length <= 200
num1 and num2 consist of digits only.
Both num1 and num2 do not contain any leading zeros, except the number 0 itself.

Multiplication Solution

Explanation

We can multiply two numbers using the stacked method. We are going to start iterating from right to left in reverse order, multiplying each value in num1 with a value in num2. If the result is greater than or equal to 10, we are going to carry an additional value. For example, with num1 = 123 and num2 = 45:

Multiply Strings on Dmytro's Blog

LeetCode - 150 - Multiply Strings

The problem

Multiplication Solution

Explanation