Please do NOT post your answer, but do say if you think you have solved the puzzle and how long it took. Solution on Monday.
How can you express the number 100 using six nines and no other digits?
I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for the Kindle (UK here and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.
Richard Wiseman 
yup.. 90 seconds.. mostly looking for the catch..
Spoiler alert.
This isn’t a spoiler – it’ s just saying that if you carry on reading someone will have posted the answer somewhere below !
Took my 20 seconds fiddling. Nice one tough.
You lying toad, ChrisR.
I read all the drivel below and there is not a single spoiler.
2 seconds btw
Hi, I Luv. A couple of hinted *attempts* at spoilers are below… but they’re wrong. Are they good enough for you, wee man?
99.9999 isn’t a spoiler Joe, it’s just a wrong answer.
Besides, if there were any decent spoilers the self-righteous brigade would be whingeing away like billyo – and they are not as yet.
Got in in (9X9)+9+9+(9/9) seconds
All the spoilers are wrong or use mathematical symbols, demonstrating that their proud owners have not even read the question.
Dave, Goddard and the other spoilers. I’m not overly bothered about the spoiling (most interested parties have had a while to try the puzzle) but do you think you could spoil it with the *correct fucking answer* please? You moronic little bell-ends, you.
Nice try Peshmeister, but your double-bluff fools no one.
Smiley, look up ‘double bluff’ in a dictionary. The word you were after was ‘bluff’, you genius you.
Iceberg, Goldberg, bluff, double-bluff – it still doesn’t fool anyone.
Or does it?
great puzzle, we find two different ways in less then 30 seconds
20 seconds. Good one, though.
5 seconds 😉
Got a solution almost instantly. I must be so wrong that Monday will be humiliating!
3 ways in 30 seconds
About a minute of floundering and then a re-read and … the solution.
0.999999 seconds
less than 99 seconds
10 seconds
There are lots of solutions…
With nothing better to do I have found 28 unique answers so far. Sad? Possibly! Anyway, I’d be surprised if there aren’t yet more.
looking forward to seeing them on Monday.
Five methods in about 1 minute.
It took me about five minutes. I like this one!
I also liked this puzzle
Bryan A.
Just a few moments
It took me a few seconds to find a possible answer, dependent on if Richard allows a close approximation 🙂
I think I got it. But will have to wait until Monday to see if my abstract thinking was permissible.
Took about 30 seconds. I like the elegance of the solution.
Took me around 99.9999 seconds.
Easy (thank goodness). 5 seconds.
I can do it using 5 9s in a couple of seconds. I’m stumped about doing it with 6 nines.
I can’t do it with 5. At least not in 5 seconds…
Hi Indigo. I’m the other way around. Please could you explain how to do it with five 9s on Monday. I can’t do it with five. (And quite honestly, I’ve wasted enough of my employer’s time trying to do it!)
I can do it with 5 as well… I’m not going to explain how though, because it is a solution for 6 9s as well… (and for 7 9s, 8 9s, and for every number of 9s as long as there are 5 or more)
I’ve got the answer, and a few others that might be right too. As usual it depends what assumptions you make.
I stumbled upon the answer after 3 minutes of scribbling.
About 99 seconds. Found it quite easily; I must be getting better at these puzzles.
Within 10 seconds — just a piece of cake. 😉
About 3 seconds.
1st answer <5secs. Two more in a few minutes. Richard – offer a Christmas prize for the most correct answers – several people claim multiple answers! If a tie, draw a name from a hat.
within 99 seconds, i was able to come up with 3 “unique” solutions (excluding commutative or associative answers). i was aiming for a total of 9, but i am lacking coffee so my brain is objecting to any more work.
Done.
30 seconds — that was easy
I solved it so fast, cause and effect was suspended and the solution came to me before I’d even read the question…
10 seconds.
i got it in 99+(99/99) seconds
Icanse eone answera nd itcame tome stra ightaw ay!!
No, this is not a spoiler, but it is code. 🙂
Barry Goddard, premature ejaculation is a common and embarrassing problem. Go see a doctor.
one second (assuming I am right)
I’ve seen this puzzle before. I think you’ve posted it in a “bets you always win” video.
2 second
3,2,1
sd
0.1692 seconds roughly
99 + (99/99).
Bah Humbug if you’re dim enough to read this far without realising that you might get spoilers.
999 / 9.99
I got two ways very quickly, There are probably more.
I found an answer in about 5 seconds that uses only one symbol other than the six 9’s themselves. I’m guessing this is the simplest possible answer.
Fairly simple. I guess it should have more than one answer.
Pleasantly surprised at how quickly that one came! about ten seconds…
About 5 seconds. Too easy!
(999-99)/9
I like this solution. Well spoiled!
This can be done with no 9s at all as the instructions are poorly written.
If i do it with sixes instead of nines, I get 49.
Saw it immediately.
5 MINS
15 seconds
5 seconds
About 3 seconds and got in second try mentally. 99/99+99