How to mentally calculate the day of the week for any date
How to mentally calculate the day of the week for any date launched on August 24, 2026 with 80 votes, #515 of 23,274 launches that month and more than 95% of that year's launches.
In plain words
This website teaches a mental math technique for calculating the day of the week for any date without a calendar or memorization. Users learn two core concepts and practice to develop the skill of determining weekdays in seconds. The resource uses interactive tables and examples to explain how remainders and number patterns work, making the traditionally complex calculation accessible to anyone willing to practice.
written from the facts on this page · September 2026
From the sources
Learn John Conway
Some people can hear any date and tell you the weekday in about two seconds , without looking at a calendar. It isn't memorization. There are two things to learn, and then some practice. By the bottom of this page, you can do this too. Weekdays go around in a circle of 7 . This is what remainders are actually good for. Try these three, and answer before you look. 🔍 Look at the table. Jumps of 7, 70, even 365 days… what actually decides where you land? Here's all of . The dates marked in gold have something in common. Tap any date to check it yourself. Find the nearest squad date, count the leftover days, then walk that many steps from the Doomsday. Let's do one together. One more thing you…from tinkerandsee.com
Does a similar job
all alternatives →
Weekle – a web app to learn how to calculate the day of the week2023 · benjoffe.com · ▲122Mentally calculating the day-of-the-week for any date in history sounds like an impossible task for a normal person, but the algorithm is actually pretty simple to learn. Although there are tutorials for this elsewhere online, and little quizzes available, there didn't seem to be anything well optimised with multiple practice modes etc. I originally created a basic version of this just for myself, but a small group of friends and family found it interesting and gave suggestions such as the daily game. Multi-lingual support is a bit rudimentary at the moment, it will only translate the month…
I made a website to learn and practice mental math2024 · mentalmathpro.com · ▲29Build your mental math skills with free online practice, step-by-step strategies, and a daily challenge. Start a quick round with Mental Math Pro.
5 Mins Maths2019 · apps.apple.com · ▲110Train 5 minutes of mental math every day, fully customizable
Buzz! Mental Maths2019 · apps.apple.com · ▲67The perfect companion for kids learning mental arithmetic
More life & fun this month
the category →
A free city-building game in your browser. You are the mayor. You know what the city needs. Now get it past the zoning board, the neighbors, the appeals court and the next election.
Life & fun · 4d ago · permit.petercai.com
- IV
Life & fun · 16d ago · tanzaniaeducationproject.org
Turn a phone, tablet or TV into a sign. Type a message and it fills the screen: welcome signs, timers, Wi-Fi passwords and more. No app, no account, free.
Life & fun · 17d ago · bigwords.page
Play a free virtual guitar online with your keyboard or by touch. Slow songs down and see every chord, string and strum. Acoustic, classic, electric and bass.
Life & fun · 11d ago · guitoro.com
Carrier settings from iPhone, Pixel and Galaxy firmware, decoded and compared: APNs, VoLTE, 5G and Wi-Fi Calling per carrier, and what each build changed.
Life & fun · 15d ago · carrierexplode.com
Life & fun · 25d ago · space.bl2.net
Source: Show HN post ↗
Launched alongside, August 2026
the whole month →- TL
Life & fun · Aug 2026 · louisabraham.github.io
Clipto MCP▲655Hey HN, We recently built Clipto. It’s a tool that lets you search over terabytes of video, audio, and images on your computer, without relying on the cloud. Motivation: we probably all had this similar experience, we know a moment exists in a video or audio, but finding it takes hours scrubbing the timeline. You can send all the media to process in the cloud, but it’s slow, expensive and raises privacy concerns. So we decided to build our own on-device media search engine. How it works (high level): 1. We ingest video, audio, image; normalize formats via ffmpeg; run content analysis to…
Work · Aug 2026 · clipto.com
Hello HN! I found that picking out plausible but diverse skin tones for my digital art and game development projects was kind of difficult, and I got curious about if there was a way to define a color space that made it easy. I've built a color picker and procedural generation algorithm based on the space as well as a bunch of other fun js features and demos throughout the page that use the equations. If you find it interesting, I have lots of explanations of how I built it and what properties the space has. The methodology might be a bit shaky, but hopefully the result is as helpful for…
Life & fun · Aug 2026 · toneyalexander.github.io
Astute▲606Automate your B2B brand going viral, with new media creators
AI · Aug 2026 · company-app.joinastute.com