decompose any unknown into multiplicative factors w/ low/mid/high - get a 90% range
How: name what you want to estimate (market size, # of piano tuners in chicago, eyeballs your pitch will reach).
Break it into multiplicative factors. For each, give a low / mid / high guess (90% confidence range).
The tool runs 10,000 monte carlo trials sampling each factor lognormally, returns the distribution of products.
The geometric mean is your point estimate; the 5th-95th percentile is your honest range.
Example: "monthly revenue from this side project" = (visitors/mo) × (signup conv) × (trial-to-paid) × ($/user).
Your gut says low/mid/high for each, the tool tells you whether the spread is meaningful or whether you've fooled yourself with false precision.