One of the tough teasers that candidates used to be asked was: 'How many piano tuners are there in the entire world?'
The riddle is known as a Fermi problem, named after the physicist Enrico Fermi who was known for his ability to make good calculations with very little information or even none.
Its purpose is to test a candidates approximation skills as well as their ability at dimensional analysis.
The puzzle is solved by multiplying a series of estimates to get to the right answer. So a candidate would have to estimate factors such as how many households have a piano, how often they are tuned to figure out how many piano tunings take place a year.
They then need to calculate the average working hours of a piano tuners and the number of jobs they carry out.
The number of piano tunings that take place per year divided by the number per year per piano tuner should yield the answer.
Google candidates going for a role as product manager also used to be asked: 'How many golf balls can fit in a school bus?
To solve it one must calculate the volume of the average golf ball and the the volume of the average school bus, taking into account factors like the seats and other fixtures taking up space.
The answer is the volume of the bus, divided by the volume of the balls.
A riddle about pirates sounds complicated but the answer is in fact quite simple.
You’re the captain of a pirate ship, and your crew gets to vote on how the gold is divided up.
'If fewer than half of the pirates agree with you, you die. How do you recommend apportioning the gold in such a way that you get a good share of the booty, but still survive?
The solution is to share 51 percent of the treasure.
Another logic puzzled candidates were given to solve was: 'How many times a day do the hands of a clock overlap?'
The hands overlap once an hour, but 11 times in 12 hours and 22 times in a day. This is because the overlap at 12 has already been accounted for.
The overlaps occur at 12, 1.05, 2.11, 3:16, 4:22, 5:27, 6:33, 7:38, 8:44, 9:49 and 10:55 in the morning and after midday at 12, 1.05, 2:11, 3:16, 4:22, 5:27, 6:33, 7:38, 8:44, 9:49 and 10:55.