A good guess, built step by step.

Restate the question, agree the scope and the units, and say how you’ll break it down. Interviewers often give details if you ask; if they don’t, choose them and say so.

Choose a structure where each piece is easy to guess and easy to defend; the share paid by UPI then gives the answer. Every number in the calculator is an assumption, not a fact: change them.

Compare the answer with something you know: takings per seat, footfall in a mall, your own experience. Here the defaults give 50 bills and about ₹60,000 on a Saturday, which sounds like a busy family restaurant. If a check fails, say which assumption you’re changing and why; interviewers value that more than a lucky first number.

Two roads that agree within a factor of two make an estimate believable; two that disagree point to the weak assumption. Top-down starts from a big known number (a city’s population, a market’s size) and narrows; bottom-up builds from one unit (a seat, a shop, a customer) and scales up.

Here seats and sittings move it most (from about 23 to 60, and 19 to 56), but you can count the seats and ask the hours. How often each seat fills is both uncertain and strong (25 to 50), so end with it: “About 38 a day, between 25 and 50 depending on how busy the sittings are.” A range with its reason beats a single number.