# Coding Challenge: The Luhny Bin

DevFeed: [Coding Challenge: The Luhny Bin](<https://devfeed.tech/articles/coding-challenge-the-luhny-bin-15580.md>)

Original publisher: [Read original article](<https://developer.squareup.com/blog/coding-challenge-the-luhny-bin>)

Author: Square Engineering

Published: 2011-11-14T17:00:00Z

Content type: article

Language: en

Sources: [Square Corner Blog RSS Feed](<https://devfeed.tech/sources/square-corner-blog-rss-feed.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [Algorithm](<https://devfeed.tech/topics/algorithm.md>), [coding](<https://devfeed.tech/topics/coding.md>), [ASCII](<https://devfeed.tech/topics/ascii.md>), [Command-line interface](<https://devfeed.tech/topics/cli.md>), [Streams](<https://devfeed.tech/topics/streams.md>), [GitHub](<https://devfeed.tech/topics/github.md>)

Tags: [algorithm](<https://devfeed.tech/tags/algorithm.md>), [ascii](<https://devfeed.tech/tags/ascii.md>), [coding](<https://devfeed.tech/tags/coding.md>), [command-line](<https://devfeed.tech/tags/command-line.md>), [engineering](<https://devfeed.tech/tags/engineering.md>), [github](<https://devfeed.tech/tags/github.md>), [logs](<https://devfeed.tech/tags/logs.md>), [numbers](<https://devfeed.tech/tags/numbers.md>), [sequences](<https://devfeed.tech/tags/sequences.md>), [test](<https://devfeed.tech/tags/test.md>)

## AI overview

This coding challenge asks readers to write a command-line program that reads ASCII text, identifies digit sequences resembling credit card numbers using the Luhn checksum, masks every digit in qualifying sequences with X characters, and writes the filtered text to standard output. The challenge includes requirements for 14- to 16-digit numbers, separators, and overlapping matches.

## Source excerpt

Do you have what it takes to escape the Luhny Bin?