ZennWidget vs Fermi Practice Drill with AI

ZennWidgetは、エンジニアのための情報共有サイトであるZennの記事一覧をウィジェットに表示するアプリです。 Zennは、エンジニアが技術的な知見や経験を共有するためのプラットフォームであり、多くのエンジニアが自身の知見を発信しています。 しかし、Zennの記事を読むためには、Webサイトにアクセスする必要があります。 そこで、ZennWidgetはユーザーがZennの記事を手軽に閲覧できるようにすることを目的としています。

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/