lemma vs Estimation & Decision Game PRO

Train like a quant. Daily. Lemma is the focused, no-fluff prep app for quantitative interviews — built for students and grads targeting Jane Street, Citadel, Optiver, Two Sigma, and the rest of the trading-firm gauntlet. WHAT'S INSIDE WITH YOUR SUBSCRIPTION • Daily sprints — bite-sized timed sets of mental math, probability, combinatorics, expected value, and market-making problems • Per-category ELO — your skill is tracked across 10 disciplines, from Novice to Expert • Adaptive difficulty — problems chosen to keep you at the edge of your level, not above or below • Hints + step-through solutions — get unstuck without giving up • Streaks, XP, leagues — habit loops without the noise • Achievements — unlock as you grind • Leaderboard — see how you stack up WHO IT'S FOR • CS / math undergrads applying to trading firms • Recent grads prepping for technical interviews • Self-learners who want a daily quantitative-thinking habit • Anyone curious about how trading interviews actually feel WHY LEMMA We strip out the gamified clutter and keep what matters: hard problems, fast iteration, real numbers on your progress. The interface borrows more from a Bloomberg terminal than a typical mobile game — monospaced metrics, hairline borders, dark by default. Most prep books drown you in 800 pages. Most courses lock you in for months. Lemma is 10 minutes a day, sharpened every day. — Lemma offers an optional auto-renewable subscription for unlimited daily sprints and premium problem sets. Subscriptions auto-renew unless cancelled at least 24 hours before the end of the current period. Manage or cancel anytime in your Apple ID settings. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://rogeru13.github.io/lemma-legal/privacy-policy/

Most people who say they are "90 percent sure" are right only about half the time. GAUGE measures and trains the one skill almost nobody tracks: knowing what you don't know. WHY YOU'LL LIKE IT (all free) - Finally see what you don't know - GAUGE scores how well your confidence matches reality, then trains it. - Find out if you are better calibrated than a frontier AI, right inside the free Lab. - Private by design: on-device only, no account, no sign-up, no tracking, no ads. - No timer, ever - GAUGE measures judgment, not speed. FOUR WAYS TO ANSWER - RANGE: give a 90 percent confidence interval. - CLAIM: judge a statement true or false. - OVER or UNDER: call it above or below. - FERMI: estimate the order of magnitude on a log scale. A TRANSPARENT GAUGE SCORE - A published 0-100 score built on proper Brier scoring. - Coverage, sharpness, and a clear letter grade. - A "how it's scored" screen so nothing is a black box. THE LAB (free) - A calibration curve: your stated confidence versus your real accuracy versus the perfect diagonal. - Overconfident points highlighted so you see exactly where you slip. - Coverage versus your target, plus a by-domain breakdown. - BASELINES that compare you to the roughly 52 percent human average and to a frontier AI. DAILY TEN AND STREAKS - The same ten questions worldwide, once a day. - Build streaks and share a spoiler-free result grid. - An activity heat map, active days, longest streak, and best grade. FREE AI TOUCHES - A short AI micro-insight after each set. - On-demand "why" context on any answer. - Every reveal shows the truth with its source - a micro-lesson each time. PRIVACY - On-device only: no account, no login, no tracking, no ads, no ad identifier. - For the AI touches, only anonymized aggregate statistics are sent to a third-party AI provider - never your identity, device identifiers, or raw per-answer logs. - Export your record as CSV or delete everything anytime. BUILT FOR IPHONE AND IPAD - Universal app with a warm-paper light theme and a dark terminal theme. - Clean monospace aesthetic. For anyone who loves trivia and quizzes but wants something smarter, and for forecasters and fans of decision-making, probability, rationality, cognitive bias, mental models, and self-improvement. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/