Quant interview prep guides

Mental Math Onsite Prep

Mental math onsite prep for whiteboard arithmetic, scratch organization, pacing, recovery, and final-round quant interviews.

Candidates doing final or onsite-style interviews with live problem solving.

Use the board to reduce memory load

Write intermediate values, denominators, and units. Onsite mental math should be visible enough to debug if the interviewer asks a follow-up.

Organize scratch work

Keep probability setup, arithmetic, and final answer separated. This makes corrections easier and prevents stale numbers from carrying forward.

Concrete setup

For an EV prompt, write outcomes, probabilities, net payoffs, and the weighted sum. That structure is clearer than scattered arithmetic.

Practice recovery

Onsite rounds can include long sequences. Practice catching and correcting an arithmetic error without losing the whole solution.

Common mistakes

Candidates often over-rely on mental memory when a whiteboard is available. Use the board for state, denominators, units, and corrections, not decoration.

Practice the pattern

Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.