Fermi Practice Drill with AI vs Dopa

Fermi Estimation is a way to train your thinking skills by answering open-ended questions using your own hypotheses and structured logic. Many companies, including leading consulting firms, ask Fermi estimation questions during interviews because they clearly reveal two critical abilities: the ability to think logically in a structured way and the ability to create realistic, data-informed hypotheses. This app is designed for people who want to strengthen those skills. Rather than being just a collection of practice questions, it helps you express your thinking in words and receive targeted AI feedback so you can steadily improve the quality of your reasoning over time. ■ Who is this app for? Students applying for consulting, strategy, or other roles that require strong problem-solving skills Candidates who feel unconfident about case interviews and are unsure what or how to improve Business professionals who want to sharpen their ability to structure ideas and build sound hypotheses People who frequently need to explain their ideas to others and want to boost their logical clarity Anyone interested in building “fundamental thinking skills” but unsure where to begin ■ Key Features & Structure A rich library of Fermi estimation practice problems We cover a wide range of topics, especially those that often appear in interviews. New questions will be continuously added so you can keep practicing with fresh challenges. Free-form written responses instead of multiple-choice You articulate your reasoning in your own words, just as you would in a real interview setting. This makes your practice highly practical and closer to real-world application. Objective feedback on your thinking, not just right or wrong The AI analyzes your solution and provides feedback such as “this assumption is strong” or “this step lacks rigor.” It highlights both your strengths and areas to improve, so you can reflect and grow. A curated collection of reference data and assumptions (Tips) Practical estimation requires realistic numbers and assumptions. The app includes a growing library of commonly used statistics, reference data, and baseline assumptions that you can access anytime. Over time, this collection becomes your own “dictionary of thinking,” a resource to draw from for future questions. Create, organize, and record your own questions You can create custom problems, import them from photos, and categorize them using tags and folders to match your learning goals. A design built for reflection and growth The app is not just about solving questions and moving on. Its design philosophy focuses on helping you reflect on your answers, build knowledge, and accumulate habits that strengthen your thinking over time. ■ What you can achieve with this app Check whether your hypotheses and structures are sound The AI evaluates each answer from multiple angles, such as decomposition, assumption validity, and numerical consistency. You’ll receive detailed written feedback showing both what you did well and where you can improve—helping you uncover blind spots you may not notice on your own. Develop a “thinking framework” through repeated practice As you practice a variety of randomly selected problems, all your answers are saved so you can review your progress and patterns over time. With each attempt, your ability to break down problems and build structured solutions becomes sharper and more natural. Accumulate and access useful data for estimation Realistic estimation requires a strong sense of scale. This app makes it easy to access baseline statistics and reference data about everyday life and business. You can also save new numbers and insights you discover while practicing, building a personalized knowledge base. Build a habit of expressing and recording your thoughts Privacy Policy: https://ferminapp.github.io Term of use : https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Dopa-writing helps you break the habit of endlessly opening social media, short videos, and games. Pause, write out your thoughts and feelings, and make room for a clearer mind. You don't have to give up your phone all at once. Start by putting the noise in your head into words. Stress, worry, frustration, unfinished thoughts. Write them as they are, for yourself rather than an audience. If you don't want to keep them, let them go without saving. Getting that noise out of your head can give you room to think. A clearer mind makes space for new ideas. When inspiration strikes while you write, capture it immediately with Flash Ideas. Dopa-writing is about more than simply restricting your phone. Turn a device you reach for without thinking into a tool for understanding yourself, thinking deeply, and finding inspiration. Build a new relationship with your phone, one writing session at a time. MAIN FEATURES * Dopa-writing Write down thoughts and feelings as they come, and quiet the mental noise. Shift from endless input to expressing what's already on your mind. * Release Let go of writing you don't want to keep, without adding it to your saved records. * Flash Ideas Capture ideas that appear while you write without interrupting your train of thought. Make space for inspiration as you let go of mental clutter. * App Blocking Use Screen Time to interrupt automatic access to selected apps. Take regular breaks from mindless scrolling and write about what's drawing you back to your phone. * 3 + 1 Intervention Levels Choose Beginner, Intermediate, or Advanced, plus Ultra for complete blocking. Adjust the intensity to suit your goals and gradually change your relationship with your phone. * Graduation Roadmap Build a plan from your current Dopa Time and your goal, and see the time you've reclaimed. With Pro, your daily limit steps down 30 minutes each Monday from the day you start, and you can see the days you stayed within it. * Reflection Look back on your Dopa-writing and journals week by week, with characters written, times you stopped scrolling, and each week's data. * Dopa Persimmon Grow your own Dopa Persimmon as you keep writing. It grows with your character count, bears fruit, and then...? * Japanese and English Support PRIVACY What you write in Dopa-writing is not sent to external servers. You don't have to post it on social media or share it with anyone. This is a private space to freely express your thoughts, feelings, and whatever is on your mind. PRO The free version includes the core writing experience and app blocking. Dopa-writing Pro unlocks the full experience, including: * More apps you can restrict * Intermediate and Advanced intervention levels that lock your limit and lower it each week along your roadmap * Charts of your daily Dopa Time, days within your limit, and your average Dopa Time * Detailed schedules by day and time * Unlimited Flash Ideas * Instant switching between journaling and Dopa-writing Get more tools to move beyond mindless scrolling and use your phone with intention. Terms of Use (Apple Standard EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/