Threads are fine if you have clean abstractions around them. Sort of like gotos are fine when abstracted out as for/while/do/etc.

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Well 10 questions is clearly a lower bound since 9 or less yes/no properties would only be able to distinguish up to 512 combinations which would not be enough for the 10-999 range.

So one easy (and minimal) answer would be 10 questions that just ask whether each of the first 10 binary bits are set..... this would cover 0-1023

More interesting would be whether you could do it with "mathematically interesting" questions such as "is it prime", "is it a square" number etc. Probably depends on what you define as mathematically interesting - I think you would have to invent some increasingly bizarre properties to distinguish between different large primes for example.

I think you could do this algorithmically:
- Create a long list of mathematically interesting properties and tests for each
- Apply the test to each number in the range 10-999 to create a "fingerprint" for each property
- Keep adding properties until you have a set that can discriminate between all the numbers 10-999 in some way (i.e. for any two given numbers, the tests for at least one property are different)
- Then it's just(!?) a case of pruning down the properties to the ones that you really need.

One approach for the last step might be to iteratively select properties with the highest discriminatory power (i.e. those that minimise the maximum size of a set of numbers that are categorised the same) until you have chosen a set that discriminates completely between all the numbers 10-999.

Probably not optimal though - anyone have an algorithm that guarantees to find the optimal answer (i.e. minimum number of properties) within a reasonable timescale?

"It always happens when you need it the most: the battery of you cellphone just died. But now, researchers of the University of Rochester have developed a wireless chip that needs ten times less power..."

Ok, but that still doesn't solve the "I need my phone now but I was too lazy to charge it last night" problem. So what, this chip can run from a dead battery? No.

It really doesn't matter how much power the phone uses... the fact is that it still uses power. Consuming power from a limited source means that it will reach a point when the battery is depleted, except now it just takes 10 days longer than before.

Murphy says, you will still be inconvenienced.