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Lambdia is quant interview practice you can actually see. Every explainer takes one question a trading desk actually asks and works it through, animated so the reasoning does the explaining.
What the desks actually test
Two things. The maths — probability, combinatorics, expected value, mental arithmetic under a clock. And the machine — the coding round, C++, concurrency, and the hardware that makes a trade fast.
Neither round scores the number you land on. They score how you got there: whether you said a verdict before the working, whether your error bars were honest, whether you held your ground when told a right answer was wrong. That is why the explainers show the trap before they show the method.
Who this is written for
You don't need a finance degree to follow any of it. If you are a maths, physics or engineering student staring at a trading internship application and wondering what they could possibly ask, this was built for you.
It also works if you are converting from a PhD, moving across from a development or hardware seat, or going back for a second attempt after reaching an on-site and not converting.
Where to start
If your first round is weeks away, start with mental math and estimation — it is the filter that runs before anyone reads your CV, and it is the one thing that cannot be crammed. Then probability, then expected value and market making.
If you have a specific interview tomorrow, go to the classic problems. They have been asked for decades, they come back, and knowing the shape of one is worth more than half-remembering ten.