Probability Theory Foundations vs Roman Numerals & Dates

Probability Theory Foundations is an independent study app for learners who want structured practice in core probability ideas, problem-solving habits, and exam-style reasoning. Built for students, self-learners, and anyone reviewing fundamentals, the app includes 160 questions across Fundamentals, Practical Skills, Common Pitfalls, and Advanced Concepts. Every question includes an explanation so you can understand why an answer works, not just whether it was right. Features: - FSRS spaced-repetition intervals to help review at the right time - Weak-point heatmap to spot topics that need attention - Daily challenge for consistent practice - Mock exams for timed review - Offline practice with no login required - Explanations for every question Practice offline, no login required. Independent study app for Probability Theory Foundations practice. Not affiliated with, endorsed by, or sponsored by any company, certification body, exam operator, or vendor. All trademarks belong to their respective owners.

Roman numerals, both ways, instantly. Type a number and the numeral appears. Type a numeral and the number appears. There is no convert button and no direction to choose — the two fields are the same fact seen from either side. IT EXPLAINS ITSELF Every result is broken down by place value: MCMLXXXVII is M + CM + LXXX + VII, not a wall of nine letters. And when a numeral is wrong the app names the rule rather than simply refusing — IIII repeats a symbol four times, IL is not one of the six subtractions the notation allows, and 49 is XLIX. IIII OR IV Almost every clock face ever made prints IIII. It is not a Roman numeral, and it is not a mistake either: it is a dial convention older than the subtractive rule. The app shows both, labelled, rather than pretending the question does not exist. PRACTICE THAT MARKS YOU A practice mode that sets questions in both directions and checks the answers, at four levels from ten to 3,999. Wrong answers show the right one. WHERE NUMERALS ACTUALLY TURN UP Years on films and cornerstones, monument dates, chapter and volume numbers, clock dials. Type a year, read it back. PAST 3,999 Standard notation stops at MMMCMXCIX. The vinculum puts a bar over a numeral to multiply it by a thousand, so 4,000 is IV barred; the older apostrophus form writes 1,000 as CIƆ. Both, up to 3,999,999. IN YOUR OWN DIGITS The number field accepts Arabic-Indic, Persian, Devanagari, Bengali, Gurmukhi, Tamil, Telugu, Thai and fullwidth digits, not only ASCII ones — and the numeral field takes the precomposed Unicode numeral characters some keyboards produce. NO ACCOUNT, NO INTERNET, NO ADVERTS The app never makes a network request and stores nothing about you. A dead app costs nothing to keep alive, so this one stays up and stays free. Converting numerals is free and always will be. The purchase is one payment for the practice mode, the dates reference and the two big-number notations — never a subscription.