5. PIANOTUNERS IN SF
• 1M people in SF
• 2 people per household
• 1/20 households have a piano
• each piano tuned once a year
• 2 hours to tune a piano
• tuners work full time for 40 hours a week
6. THE MATH
• 1M people / 2 people per household = 500K households
• 500K * 1 / 20 pianos/household = 25 000 pianos = 25 000 piano
tunings per year
• 1 hour to tune a piano = 100 000 piano tuning hours
• 100 000 hours / 2 000 hours per piano tuner = ~50 piano tuners!
7.
8. USEFUL FOR…
• Interviews!
• Satisfying personal curiosity
• Trying to figure out whether or not
Maroon 5 really crashed all those
weddings…
9. TACTICS
• Top down vs. Bottoms up
• Give a range!
• Easy numbers = Good numbers
• Key is make assumptions based on what you know
11. LOL.WHAT A DOUCHE.
• Jonathan is a Male name
• 50% of population is Male
• Only Westernized civilizations will name kids Jonathan (2B people)
• 1/16 Males named some variation of Jonathan (Jon, John, Johnathan etc)
• 3B * 50% * 1/16 = 62.5M people named Jonathan
13. "FERMI ESTIMATES WORK BECAUSETHE ESTIMATIONS OFTHE
INDIVIDUAL TERMS ARE OFTEN CLOSE TO
CORRECT, AND OVERESTIMATES AND UNDERESTIMATES HELP
CANCEL EACH OTHER OUT. "