# Introduction In this lab, we will be exploring the use of the `Array.prototype.reduce()` method to calculate the sum of two or more numbers/arrays. We will learn how to initialize an accumulator with a value of `0` and how to use the spread operator to pass an array as individual arguments. By the end of this lab, you will have a better understanding of how to use the `reduce()` method in JavaScript.
Click the virtual machine below to start practicing