# Commas in big numbers everywhere: An OpenType adventure

DevFeed: [Commas in big numbers everywhere: An OpenType adventure](<https://devfeed.tech/articles/commas-in-big-numbers-everywhere-an-opentype-adventure-20160.md>)

Original publisher: [Read original article](<https://blog.janestreet.com/commas-in-big-numbers-everywhere/>)

Author: Tristan Hume

Published: 2019-10-14T00:00:00Z

Content type: article

Language: en

Sources: [Jane Street](<https://devfeed.tech/sources/jane-street.md>)

Topics: [Font](<https://devfeed.tech/topics/font.md>), [data](<https://devfeed.tech/topics/data.md>), [jupyter](<https://devfeed.tech/topics/jupyter.md>), [Terminal](<https://devfeed.tech/topics/terminal.md>), [browser](<https://devfeed.tech/topics/browser.md>)

Tags: [browser](<https://devfeed.tech/tags/browser.md>), [documentation](<https://devfeed.tech/tags/documentation.md>), [efficiency](<https://devfeed.tech/tags/efficiency.md>), [feature](<https://devfeed.tech/tags/feature.md>), [fonts](<https://devfeed.tech/tags/fonts.md>), [jupyter](<https://devfeed.tech/tags/jupyter.md>), [jupyter-notebooks](<https://devfeed.tech/tags/jupyter-notebooks.md>), [numbers](<https://devfeed.tech/tags/numbers.md>), [terminal](<https://devfeed.tech/tags/terminal.md>)

## AI overview

This article describes Numderline, a font that uses OpenType shaping features to insert commas into numbers and emphasize digit grouping. It explains the basics of font shaping, including glyph substitutions and positioning, and discusses how reverse substitution enables grouping digits from the end of a number.

## Source excerpt

My job involves a lot of staring at large numbers, mostly latencies in nanoseconds, and picking out magnitudes like microseconds. I noticed myself constantly counting digits in my text editor, in my terminal, and in Jupyter notebooks in my browser.