Build one case skill at a time, from timed maths practice and mental arithmetic to frameworks, charts and the final recommendation. Every answer is explained, so each rep teaches the method.
Give the CEO a 60-second recommendation: answer first, three reasons with numbers, risks and next steps.
Drills
Time
Right
Sanity checks
A sanity check compares a number with something you already know: a per-person figure, a capacity limit, an order of magnitude. Interviewers plant wrong numbers and unit slips on purpose and expect you to catch them unprompted. The habit also protects your own estimates, since most sizing errors are a dropped zero or a wrong unit.