---
title: "Doomsday Trainer - Reviews, Revenue and Downloads in Australia | Apple App Store"
description: "Master the Doomsday Algorithm — calculate the day of the week for any date in history in seconds.  PLAY Build your streak and beat the clock. Every correct answer adds to your streak; one wrong answer"
---

# Doomsday Trainer — Australia
> Know the day for any date!

![Doomsday Trainer App Icon](https://is1-ssl.mzstatic.com/image/thumb/Purple211/v4/9f/6e/e4/9f6ee4e8-ec37-e533-35fb-abdeaf92fd28/AppIcon-0-0-1x_U007epad-0-1-85-220.png/434x0w.png)

**Developer:** [Maarten Claessen](https://apptail.io/developer/maarten-claessen-aBIeTb)
**Category:** Education
**Rating:** N/A (0 ratings)
**Price:** Free
**Bundle ID:** com.inefficientcode.doomsdaytrainer
**Store:** Apple App Store
**Country:** Australia
**Version:** 1.3.9 (released 2026-09-15)
**Original Release:** 2026-03-27
**Languages:** English

**App Store Link:** [Download on Apple App Store](https://apps.apple.com/au/app/app/id6760719687)
**AppTail Page:** [https://apptail.io/app/doomsday-trainer-Rvnz/australia](https://apptail.io/app/doomsday-trainer-Rvnz/australia)

## Doomsday Trainer Description
Master the Doomsday Algorithm — calculate the day of the week for any date in history in seconds.

PLAY
Build your streak and beat the clock. Every correct answer adds to your streak; one wrong answer ends it. Compete on the global leaderboard for Longest Streak and Fastest Average Speed.

BATTLE
Challenge a real opponent to a live 1-on-1 race. Five dates, fastest and most accurate player wins. Elo-based ranking tracks your competitive record.

TRAIN
Six methods to choose from:
• Doomsday — the classic anchor-day approach
• Odd + 11 — the Fong-Walters mental shortcut
• The Wollin Shortcut — a memory-based system using vectorized doomsdays, the Square Knot Rule, and the Wollin Calamity Table (by u/Nillows)
• Conway's Method — the original algorithm by John Conway
• Mod 28 — reduce any year to under 28 before calculating
• Custom Mode — pick your own date range, century, or decade

DRILL
Targeted practice for each component: months, centuries, years, mod 7 arithmetic, and the full Wollin Shortcut drill suite.

TUTORIAL
New to the algorithm? The built-in tutorial walks you through everything step by step.

## Doomsday Trainer Screenshots
- [Screenshot 1](https://is1-ssl.mzstatic.com/image/thumb/PurpleSource221/v4/35/58/ad/3558ad1a-2da3-1162-7c60-fc02f5bfba50/ipo1.jpg/1242x2688.png)
- [Screenshot 2](https://is1-ssl.mzstatic.com/image/thumb/PurpleSource221/v4/58/da/04/58da04d8-a088-c91a-32c7-f1d90a0a0c72/ipo2.jpg/1242x2688.png)
- [Screenshot 3](https://is1-ssl.mzstatic.com/image/thumb/PurpleSource211/v4/c5/c6/1a/c5c61a53-80fd-0771-ff3f-ec5b164ab429/ipo3.jpg/1242x2688.png)
- [Screenshot 4](https://is1-ssl.mzstatic.com/image/thumb/PurpleSource211/v4/b1/7e/45/b17e4541-1e6d-f35c-d199-72f1a73402a4/ipa7.jpg/1242x2688.png)
- [Screenshot 5](https://is1-ssl.mzstatic.com/image/thumb/PurpleSource211/v4/bb/83/5b/bb835b03-015c-efd2-23ed-a4219f26ad99/ipo4.jpg/1242x2688.png)







## Doomsday Trainer Available In
- [United States](https://apptail.io/app/doomsday-trainer-Rvnz/united-states)
- [Grenada](https://apptail.io/app/doomsday-trainer-Rvnz/grenada)
- [Hong Kong SAR China](https://apptail.io/app/doomsday-trainer-Rvnz/hong-kong)
- [Jamaica](https://apptail.io/app/doomsday-trainer-Rvnz/jamaica)
- [Jordan](https://apptail.io/app/doomsday-trainer-Rvnz/jordan)
- [Japan](https://apptail.io/app/doomsday-trainer-Rvnz/japan)
- [South Korea](https://apptail.io/app/doomsday-trainer-Rvnz/south-korea)
- [Kazakhstan](https://apptail.io/app/doomsday-trainer-Rvnz/kazakhstan)
- [Sri Lanka](https://apptail.io/app/doomsday-trainer-Rvnz/sri-lanka)
- [Panama](https://apptail.io/app/doomsday-trainer-Rvnz/panama)
- [Pakistan](https://apptail.io/app/doomsday-trainer-Rvnz/pakistan)
- [Slovakia](https://apptail.io/app/doomsday-trainer-Rvnz/slovakia)
- [Taiwan](https://apptail.io/app/doomsday-trainer-Rvnz/taiwan)
- [Australia](https://apptail.io/app/doomsday-trainer-Rvnz/australia)
- [Venezuela](https://apptail.io/app/doomsday-trainer-Rvnz/venezuela)

---

## About AppTail

[AppTail](https://apptail.io) is a mobile app intelligence platform providing app analytics, ASO (App Store Optimization) tools, keyword tracking, competitor analysis, revenue estimates, and review monitoring for iOS App Store apps. Track your app's performance, discover ranking keywords, monitor competitors, and analyze market trends.

- [Search Apps](https://apptail.io)
- [Top Charts](https://apptail.io/top-iphone-apps)
- [Sign Up for Full Access](https://app.apptail.io/signup?utm_campaign=ai-crawl&utm_content=footer)

*Data provided by [AppTail](https://apptail.io) - Mobile App Intelligence Platform*