Study guide
How to use these cards.
Which tab to read and when, how to switch languages, how to adjust for your own level, and what to do when an explanation still doesn't land. The first four questions are free, no account required — so you can try all of this before you decide anything.
After you answer
Every question opens into three tabs.
Once you pick an answer, the card opens a short explanation split into three depths. The tab each screen below shows is ringed in navy — you don't have to read all three every time, so pick the one that matches what you need right now.
1Answer
Just the result, the formula, and the trap in the question — read this first, always. Often it's all you need.
2Worked solution
The full step-by-step: a map of the case, then each calculation with every number traced back to where it came from. This is the “how.”
3Background
The underlying concept, taught from zero. This is the “why” — read it and you don't need a separate textbook open beside you.
On non-calculation questions the middle tab is labeled Explanation instead of Worked solution, but it does the same job: it walks through the reasoning behind the correct choice.
Switch languages
One toggle: English, Chinese, Japanese.
At the top of every card there is a language switch — EN, 中文, and JP (ringed below). One tap flips the question, the answer choices, and all three explanation tabs together, so you can read a question in one language and check the explanation in another whenever a term is unclear.
EN, 中文 and JP are on every card. Switching never resets your answer or your progress.
Match it to your level
Read fewer tabs as you get stronger.
New to the material
Read all three, in order — build the concept from zero, question by question.
Answer
Worked solution
Background
Confident or experienced
The Answer tab alone usually confirms it. Dip into the other two only when a question surprises you.
Answer
Worked solution
Background
Stuck on an explanation?
Copy the card and ask your own AI.
Every card has a Copy button at the top (solid ring below). Tap it to copy the question and its answer as plain text — the whole dashed area — then paste it into ChatGPT, Claude, or any AI chat to ask a follow-up in your own words. Copy only includes the answer once you've answered — it never hands you the result early.
Paste into your AI chat
“Explain this step more simply” · “Why is choice B wrong?”
Try it on a real question.
The first four questions are free, no account required.