Hexadecimal | ByteTrail

Summary

Hexadecimal, usually called hex, is another way to write numbers. It uses sixteen symbols: 0–9, then A–F. One hex digit represents exactly four binary bits, so hex makes long binary values easier for people to read.

Introduction

Binary works well inside circuits but is tiring for people to scan. Hex keeps the exact same value while putting the bits into short, readable groups.

Explanation

After 9, hex uses letters: A means decimal 10, B means 11, through F, which means 15. To change binary into hex, split the bits into groups of four from the right. For example, 1111 0010₂ becomes F2₁₆: 1111 is F and 0010 is 2. Since a byte has eight bits, two hex digits represent one byte.

Real-world example

Web colors

The color #2A7FFF contains three byte-sized hex pairs: red 2A, green 7F, and blue FF. Designers can exchange an exact color without writing 24 binary digits.

Group bits in fours

Interactive exploration

A byte written as hexadecimal

Step 1 of 4

1111. The first four bits have the value fifteen.

Hex is not more precise than binary; it is simply a shorter label for the same bit pattern. It is useful when people need to inspect binary data because four-bit groups are quick to convert.

Code example

const value = 242;
console.log(value.toString(16).toUpperCase()); // F2
console.log(Number.parseInt('F2', 16)); // 242

Common mistakes

Reading B as a letter rather than decimal 11 in a hex number.
Grouping binary digits in threes; that is useful for octal, not hex.
Assuming every # value is a color; context determines its meaning.

Quiz

Knowledge check

You split `1010 0111₂` into two four-bit groups. Which hex value represents the same bits?

A7107F7

Try it

Decode a byte

Convert 7B₁₆ to binary by replacing each hex digit with four bits, then find its decimal value.

Key takeaways

Hex uses sixteen symbols: 0–9 and A–F.
One hex digit maps exactly to four bits.
Hex is compact notation for binary values such as bytes and addresses.