Everyone should learn this method
We all use calendars, we should be able to calculate dates mentally with accuracy. This app helps you master the algorithm.
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About
Learn to calculate the weekday for any date without a calendar or phone. This app teaches a step-by-step method with interactive drills and games to master the skill. Unlock advanced features with a one-time purchase.
✓Step-by-step weekday calculation method
✓Interactive drills and flashcards
✓Two engaging practice games
✓Progress tracking and weak-spot identification
✓Reference tables for calculations
✓Support for historical calendar rules
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What's New in Day Genius
1.2
September 15, 2026
Already know your month codes as January = 6? Day Genius now teaches from that list too. In the Month codes step, choose the classic list (January = 0, still the default) or the alternate list, every code one lower. Year codes match automatically, and every lesson, check question, flashcard, drill, game, Reference table and widget follows your choice. Switch anytime; the steps you've mastered stay mastered. ALSO NEW • Famous dates: a Full date flashcard deck of twelve dates from 1776 to 2001, with what happened on the back • Twelve memory hooks written for the alternate list • Where the codes come from, now a card of its own, plus a note on why two lists exist • A quick calendar check for any year code, and a dozens ladder for working year codes out in your head • New check questions (if July 4 is a Saturday, what day is Halloween?) and clearer wording in all eight steps REFINED • Drill and Speed Round answers now fit on screen without scrolling • Date Drop keeps every weekday bucket in view on smaller iPhones • Tidier iPad layouts • VoiceOver now reads the Leap year and Your own century tags on flashcards • Many corrections and clarifications across the lessons
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Subscriptions & In-App Purchases
$3.99
Full Method
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FAQ
How does Day Genius teach weekday calculation?
Day Genius breaks down the process into eight manageable steps, each with memory hooks and interactive drills. You must achieve 90% accuracy in a step before unlocking the next.
What is the cost of Day Genius?
The first four steps of Day Genius are free to use. Steps 5-8, which include year codes and century shifts, can be unlocked with a one-time purchase.
Does Day Genius have ads?
No, Day Genius does not contain advertisements. It is a free app with an optional one-time purchase for full feature access.
What devices does Day Genius support?
Day Genius is available on iPhone and iPad devices, making it accessible for users on the Apple ecosystem.
How does Day Genius handle historical dates?
Day Genius correctly calculates dates according to the calendar used in Britain and its colonies, including the skipped days in 1752 and leap year rules before that era.
Can I practice specific areas I find difficult in Day Genius?
Yes, Day Genius identifies months, years, and centuries you struggle with and incorporates them into later drills. It also offers a one-tap weak-spot drill.
What are the games in Day Genius?
Day Genius includes two games: 'Speed Round,' where you race against the clock to identify weekdays for random dates, and 'Date Drop,' a falling-block game where you sort dates into their correct weekdays.
How often is Day Genius updated?
The latest version of Day Genius is 1.2, which was last updated on September 15, 2026. Updates typically include improvements and new content.
