So how do computers display, manage data, and do math? Glad you asked.
Store and retrieve data
Programming languages, like Ruby, Python, and C#, give computers the ability to store and retrieve data, often through SQL statements, making complex web apps possible. You sign up for a website and your user id and password are stored in a database. Maybe that site allows you to upload photos which are stored on a server. Pinterest, Instagram, and Snapchat all store user id’s, passwords, and photos but by doing so in different ways and for different purposes they are completely different apps.
Each number is represented by a binary unit. The arithmetic and logic unit, the ALU, performs calculations on those binary units. Here are some links for a more complete understanding: a YouTube video and a Stack Overflow answer. For a list of programming languages used for math this article by Brenda Barron is pretty informative.
The bottom line
A developer uses an appropriate language to write code that tells a computer to do one of 3 things: create a display, manage data, and math. Cool, right?