#AP Computer Science Principles: Data Representation Study Guide

Hey there! Let's get you prepped for the AP CSP exam. This guide is designed to be your go-to resource, especially the night before the test. We'll break down the key concepts, highlight important connections, and make sure you're feeling confident. Let's do this!

#💾 Data Basics and Number Systems

#What is Data?

Data is simply a collection of facts. It's everywhere, from lab results to your favorite videos. Computers run on data, but how do they store it? Let's dive in!

#How Computers Store Data

Computers store data in bits, which are binary digits (0s and 1s). To understand this, we need to talk about number bases.

#Number Bases

A number base is the number of digits or digit combinations a system uses to represent values.

• Decimal (Base-10): Uses 0-9. This is what we use in everyday life.
• Binary (Base-2): Uses only 0 and 1. This is what computers use at their core.
• Hexadecimal (Base-16): Uses 0-9 and A-F. Often used for color codes and representing binary in a more human-friendly way.

#Decimal System (Base-10)

Remember place values? Ones, tens, hundreds, thousands, etc. Each place is a power of 10.

For example, 5,729 = (5 x 1000) + (7 x 100) + (2 x 10) + (9 x 1)

#Binary System (Base-2)

Each place can only hold a 0 or 1. The place values are powers of 2: ones, twos, fours, eights, etc.

For example, binary 0101 = (0 x 8) + (1 x 4) + (0 x 2) + (1 x 1) = 5

• Bit: A single binary digit (0 or 1).
• Byte: 8 bits.

#Hexadecimal System (Base-16)

Uses 0-9 and A-F (where A=10, B=11, C=12, D=13, E=14, F=15). Place values are powers of 16. ![](https://zupay.blob.core.windows.net/resources/files/0baca4f69800419293b4c75aa2870acd_76ff10_3948.png?alt=media&token=3c84188d-e352-43e8-8793-541aa3d9e3b9...