Fermi estimates can help you become more efficient in your day-to-day life, and give you increased confidence in the decisions you face. If you want to become proficient in making Fermi estimates, I recommend practicing them 30 minutes per day for three months. In that time, you should be able to make about (2 Fermis per day)×(90 days) = 180 Fermi estimates.
I’m not sure about this claim about day-to-day life. Maybe there are some lines of work where this skill could be useful, but in general it’s quite rare in day-to-day life where you have to come up with quick estimates on the spot to make a sound descision. Many things can be looked up on the internet for a rather marginal time-cost nowadays. Often enough probably even less time, than it would actually take someone to calculate the guesstimate.
If a descision or statistic is important you, should take the time to actually just look it up, or if the information you are trying to guess is impossible to find online, you can at least look up some statistics that you can and should use to make your guess better. As you read above, just getting one estimate in a long line of reasoning wrong (especially where big numbers are concerned) can throw off your guess by a factor of 100 or 1000 and make it useless or even harmful.
If your guess is important to an argument you’re constructing on-the-fly, I think you could also take the time to just look it up. (If it’s not an interview or some conversation which dictates, that using a smartphone would be unacceptable).
And if a descision or argument is not important enough to invest some time in a quick online search, then why bother in the first place? Sure, it’s a cool skill to show off and it requires some rationality, but that doesn’t mean it’s truly useful. On the other hand maybe I’m just particularly unimaginative today and can’t think of ways, how Fermi estimates could possibly improve my day-to-day life by a margin that would warrant the effort to get better at it.
I’m not sure about this claim about day-to-day life. Maybe there are some lines of work where this skill could be useful, but in general it’s quite rare in day-to-day life where you have to come up with quick estimates on the spot to make a sound descision. Many things can be looked up on the internet for a rather marginal time-cost nowadays. Often enough probably even less time, than it would actually take someone to calculate the guesstimate.
If a descision or statistic is important you, should take the time to actually just look it up, or if the information you are trying to guess is impossible to find online, you can at least look up some statistics that you can and should use to make your guess better. As you read above, just getting one estimate in a long line of reasoning wrong (especially where big numbers are concerned) can throw off your guess by a factor of 100 or 1000 and make it useless or even harmful.
If your guess is important to an argument you’re constructing on-the-fly, I think you could also take the time to just look it up. (If it’s not an interview or some conversation which dictates, that using a smartphone would be unacceptable).
And if a descision or argument is not important enough to invest some time in a quick online search, then why bother in the first place? Sure, it’s a cool skill to show off and it requires some rationality, but that doesn’t mean it’s truly useful. On the other hand maybe I’m just particularly unimaginative today and can’t think of ways, how Fermi estimates could possibly improve my day-to-day life by a margin that would warrant the effort to get better at it.