Quant interview prep guides

Mental Math and Fermi Cluster Final Review

Final review for the mental math and Fermi estimation cluster, covering arithmetic, estimation, diagnostics, mocks, recovery, and statistics transition.

Candidates finishing the mental math and estimation module.

Confirm arithmetic reliability

Fractions, percentages, multiplication, division, probability ratios, EV arithmetic, and units should be stable under light time pressure.

Confirm estimation structure

For Fermi prompts, check target definition, factor tree, assumptions, units, range, sanity check, and communication before calling the cluster complete.

Concrete final drill

Run one mixed set: five arithmetic prompts, one EV prompt, one market-making calculation, one statistics calculation, and one Fermi estimate.

Transition to statistics

The next cluster builds on this work. Statistical mental math is easier when units, approximations, and sanity checks are already reliable.

Common mistakes

Candidates often finish by rereading notes. Final review should produce live evidence that repeat errors are reduced under realistic timing.

Practice the pattern

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