Every line checked.
Each step you write is parsed and graded on your device. A grade is a computation, not a guess.
Master probability & statisticswith AI that actually teaches.
Paste any question or a screenshot of one, solve it line by line in real math notation, and get every line checked on your device — with an AI tutor for when you’re stuck.
Paste a question.Start solving.
The same editor the app uses — click a symbol and get the structure, not a LaTeX command.
Try an exam-style question
One question.Every step.
New numbers, every time.
Practice the method, not one answer. Every drill rolls fresh numbers.
Ask in plain words.
The tutor already sees your question and your working. Short answers, real formulas.
Sum vs mean of normal samplesHow variance scalesStandardizing (z)Reading the Z-table
checked, not guessed
Every line you write is parsed and evaluated on your device. A grade is a computation, not a prediction — so it can’t be confidently wrong the way a chat model can.
P\left(3\sum_{i=1}^{16}X_i > 3852\right)
circle anything, ask about it
Draw round any part of a question — or of your own working, or of the tutor’s reply — and it becomes context in the chat. No retyping a formula into a chat box that mangles it. Circle it, then just ask.
point at a line, get the next one
Hover any line of your solution and suggested next steps appear — worked out for your numbers. Press 2 and the row below writes itself, and like every line it is checked on your device.
A live sample — replies are canned, nothing leaves this page.
answers in math, not essays
Ask anything and get a few sentences with real formulas — not a 500-word lecture on the history of probability. The tutor sees what’s on your screen, so you never paste context again.
Canned for the demo — nothing leaves this page.
stuck, not spoon-fed
The first hint refuses to solve it — it asks the one question that unsticks you. Press again for the formula, again for the next line. And when you think you’re done, check my solution comes back pointing at the line you got wrong, not with an essay about probability.
A population is normally distributed with mean 80 and variance 16. A researcher draws samples of size 16. Find
P\left(3\sum_{i=1}^{16}X_i > 3852\right)
✓
Every drill is a template — not an answer key.
new numbers, every time
Drills are templates, not answer keys: every attempt rolls new numbers, so you practice the method instead of memorizing one answer. And a screenshot you save becomes a question in your bank, ready to solve again.
say it, hear it back
Ask out loud when your hands are busy writing, and hear the answer read back — with the formulas spoken as math, not as “backslash frac”. The guided lesson is narrated slide by slide, too.
You keep missing CLT questions because of sum vs sample mean — so that’s what comes next.
it studies you back
Your mistakes build a map of what you actually know. The practice track picks the next question from the weak spot upstream — so you fix the cause, not the symptom.
Free to learn.One payment for more AI.
Lessons, practice, grading and formulas are free forever: they run on your device. Every account gets free AI credits each day; the Pass raises them for one payment, yours for life.
Free
Everything that runs on your device, forever. No card.
$0forever
10 tutor messages a day
2 screenshot reads a day
Always free:
- The guided lesson and drills
- Adaptive practice track
- Line-by-line grading on your device
- The 42-formula sheet
- Question bank
- Weak-spot map
PassLifetime
Far more AI help every day, for one payment.
$29one-time
100 tutor messages a day
15 screenshot reads a day
What you get:
- Everything in Free
- Yours for life, no renewal
- No subscription, nothing to cancel
Use up today's credits and only the AI pauses until midnight UTC; lessons, practice, grading and formulas keep working. Prices in US dollars.
Free for everyone,forever:
- A guided lesson on sums vs means
- Drills with new numbers every time
- An adaptive practice track
- Every line graded on your device
- Real math notation — no LaTeX
- Paste any question and solve it
- A 42-formula sheet
- A weak-spot map of what you know
- A bank for the questions you save
- The step-by-step hint ladder in drills
Frequentlyasked questions
A practice app for a first course in probability and statistics. Paste an exam question — or a screenshot of one — and solve it line by line in real mathematical notation, with every line checked as you write it.
The grading, the formula sheet and the drills run on your own device. The AI tutor is there for the parts a machine genuinely helps with: reading your screenshot, nudging you when you are stuck, and explaining a step you got wrong.
A chat model hands you an answer and can be confidently wrong about the steps in between. Here a grade is a computation: your line is parsed and evaluated, so it cannot be talked into agreeing with you.
And you write in math, not in LaTeX or in a sentence describing math. One click gives you a sum with its limits, with the cursor already in the first box.
No. Click a symbol and you get the structure, not a command to remember.
The guided, narrated lesson and the drills currently cover one topic in depth: the sum vs the mean of normal samples — how the variance scales, standardizing, and reading the Z-table.
For everything else, paste the question or a screenshot of it: the line-by-line grader and the tutor work on any topic.
One tutor message is one thing the AI does for you: a tutor reply, a hint from the tutor, or a set of next-step suggestions. Asking out loud costs one, and hearing an answer read aloud costs one per 70 characters. One screenshot read turns one photo of a question into something you can solve.
Every account gets 10 tutor messages and 2 screenshot reads a day, free. The Pass raises that to 100 tutor messages and 15 screenshot reads a day. Credits refresh at midnight UTC.
Lessons, practice, grading, the formula sheet and drills with new numbers cost nothing — they never touch the AI.
The AI pauses until midnight UTC. Nothing else does: you keep practicing and keep getting graded, because that half of the app never needed it.
There is no subscription, so there is nothing to cancel. The Pass is one payment and it's yours for life; everything that runs on your device is free anyway.
Grading that doesn’t involve the AI runs on your device. Before you sign in, your progress lives in your browser; once you sign in, it’s saved to your account so it follows you.
Screenshots you upload and the questions you ask the tutor — with what’s on your screen — are sent to our AI provider, Anthropic, so they can be answered. Speech goes to ElevenLabs. The privacy policy has the details.
Started a week before the exam?You’ll probably pass.
Start learning freeNo card. Lessons, practice, grading and formulas are free forever: they run on your device. Every account gets 10 tutor messages a day free, and the Pass is $29, once.