Last week on More or Less we played an estimating game with the economist Jim Poterba from the Massachusetts Institute of Technology (MIT) in the US, together with some listeners to the programme.
Can you estimate the number of dogs in the UK?
We also set some questions for listeners at home. Here are the answers
How much is spent in the UK on cigarettes and tobacco each year?
Answer: About £12.5 billion.
How large is the Atlantic ocean in square miles?
Answer: Either about 32 million or 41 million square miles, depending whose definition of the boundaries you prefer.
How many dogs are there in the UK?
Answer: About 6 million.
If your estimation is within a factor of two or three, you've done pretty well, says Jim Poterba.
It's the rough order of magnitude that counts.
We also have to come clean and admit that Jim's figure for the number of flights from Heathrow mistakenly gave the number both arriving and leaving the airport.
The correct number of flights from Heathrow is about 226,000.