How it works
Every round sets one fresh problem, released to everyone at the same moment. You solve it on paper with your phone filming you from the side, a person marks it, and a strong result earns a badge anyone can trust.
How a round works
Pick a round
Rounds go up in the calendar days ahead, each with its start time and length. Sign up for the ones that suit you: your first is free, and members get every week.
Set up before it starts
In the 20 minutes before, open the round on your laptop, share your camera and screen, and stand your phone to one side, so it films you, your desk and your screen.
Solve on paper
The problem appears for everyone at the same moment. Work it out by hand, then photograph your write-up with your phone.
Get marked by a person
Within three days a grader marks your write-up out of 5 and checks the recordings of you working. 4/5 or more earns a verified badge on your profile.
What you need
- A laptop with a webcam, in Chrome, Edge or Firefox, on one screen
- A phone, propped up to the side so it sees you, your desk and your screen (a shelf, a pile of books or a small tripod all work)
- Some paper, a pen, and a quiet room
The recordings are only used to check results. Nobody else sees them.
A badge that means you did it
Anyone can claim they solved something. Here, a person reviews your attempt and confirms that you solved it yourself, without external help.
Your first round is free. Members get multiple every week.
Member
$15 a month
- Access to all Core* problem rounds
- Every past problem with its official solution
- Solve as a team of up to 4
We run at least two Core rounds every week. Paid extras, like the weekly integral, are entered with separately bought credits. Stop membership any time.