Fermi Estimation
Super-scientific guesses
But Really
Interview Questions!
Also great for technology
Also great for technology
provide the basis for a discussion
Also great for technology
provide estimates for a project
provide the basis for a discussion
Also great for technology
provide estimates for a project
estimate the feasibility of an opportunity
provide the basis for a discussion
Also great for technology
provide estimates for a project
estimate the feasibility of an opportunity
determine if an answer that you have obtained makes sense
provide the basis for a discussion
The Technique:
The Technique:
Identify the components of the answer
The Technique:
Divide the problem into small steps
Identify the components of the answer
The Technique:
Identify all the information you have
Divide the problem into small steps
Identify the components of the answer
The Technique:
Identify all the information you have
Determine what you have enough information for to factor into your problem
Divide the problem into small steps
Identify the components of the answer
The Technique:
Identify all the information you have
Determine what you have enough information for to factor into your problem
Divide the problem into small steps
Make an order-of-magnitude guess for what you don't have
Identify the components of the answer
The Technique:
Identify all the information you have
Determine what you have enough information for to factor into your problem
Divide the problem into small steps
Solve each step
Make an order-of-magnitude guess for what you don't have
Identify the components of the answer
The Technique:
Identify all the information you have
Determine what you have enough information for to factor into your problem
Divide the problem into small steps
Solve each step
Combine each step into an answer
Make an order-of-magnitude guess for what you don't have
Identify the components of the answer
The Technique:
Guessing
Rounding makes things easier to calculate- we only really care about orders of magnitude
The Technique:
Guessing
Rounding makes things easier to calculate- we only really care about orders of magnitude
Item Exact Value Suggested Value (for faster calculation)
1 day 24 hours 25 hours
1 mile 5280 feet 5000 feet
1 yard 0.9144 meter 1 meter
1 foot 30.48 cm 30 cm
1 pound 453.6 g 500 g
1 hour 3600 seconds 4000 seconds
Identify all the information you have
Identify all the information you have
How many kilometers are there in a light-year?
Identify all the information you have
How many kilometers are there in a light-year?
How long is a light-year?
Identify all the information you have
How many kilometers are there in a light-year?
How long is a light-year?
c = 186,000 miles / second
Identify all the information you have
For the average American, how many times will their heart beat during their lifetime?
Identify all the information you have
For the average American, how many times will their heart beat during their lifetime?
What do we know?
What do we have to guess?
Divide and Conquer
How many heartbeats are there in a year for the entire world's population?
Divide and Conquer
How many heartbeats are there in a year for the entire world's population?
What smaller problems is this composed of?
Divide and Conquer
How many heartbeats are there in a year for the entire world's population?
What smaller problems is this composed of?
How fast does one person's heart beat?
Divide and Conquer
How many heartbeats are there in a year for the entire world's population?
What smaller problems is this composed of?
How fast does one person's heart beat?
How many heartbeats per year?
Divide and Conquer
How many heartbeats are there in a year for the entire world's population?
What smaller problems is this composed of?
How fast does one person's heart beat?
How many people are there?
How many heartbeats per year?
Divide and Conquer
How many heartbeats are there in a year for the entire world's population?
Earth's population * Heartbeats per year
Divide and Conquer
How many heartbeats are there in a year for the entire world's population?
Earth's population * Heartbeats per year
2,400,000,000 heartbeats per year in the US
Making Multiple Guesses
How many pounds of rice were consumed in the U.S. in the year 2015?
Making Multiple Guesses
How many pounds of rice were consumed in the U.S. in the year 2015?
How many people in the US?
Making Multiple Guesses
How many pounds of rice were consumed in the U.S. in the year 2015?
How many people in the US?
How much rice does a person eat?
Making Multiple Guesses
How many pounds of rice were consumed in the U.S. in the year 2015?
How many people in the US?
How much rice does a person eat?
5,200,000,000 lbs (Source: USDA)
Fermi Estimation
By LizTheDeveloper
Fermi Estimation
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