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.

1. ChrisR says:

This isn’t a spoiler – it’ s just saying that if you carry on reading someone will have posted the answer somewhere below !

2. Took my 20 seconds fiddling. Nice one tough.

3. I Luv Spoilers says:

I read all the drivel below and there is not a single spoiler.
2 seconds btw

4. Joe Peshy says:

Hi, I Luv. A couple of hinted *attempts* at spoilers are below… but they’re wrong. Are they good enough for you, wee man?

5. I Luv Spoilers says:

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.

6. Dave says:

Got in in (9X9)+9+9+(9/9) seconds

7. Bert says:

All the spoilers are wrong or use mathematical symbols, demonstrating that their proud owners have not even read the question.

8. Joe Peshy says:

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.

9. The People's Smiley says:

Nice try Peshmeister, but your double-bluff fools no one.

10. Anonymous says:

Smiley, look up ‘double bluff’ in a dictionary. The word you were after was ‘bluff’, you genius you.

11. Double Anonymous (or did I just mean Anomymous?) says:

Iceberg, Goldberg, bluff, double-bluff – it still doesn’t fool anyone.
Or does it?

1. tobi says:

great puzzle, we find two different ways in less then 30 seconds

2. Numbers guy says:

20 seconds. Good one, though.

3. Selim says:

5 seconds 😉

4. Got a solution almost instantly. I must be so wrong that Monday will be humiliating!

5. ChrisR says:

3 ways in 30 seconds

6. VicinCA says:

About a minute of floundering and then a re-read and … the solution.

7. cozdsa says:

0.999999 seconds

8. Anonymous says:

less than 99 seconds

1. A Level Maths drop-out says:

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.

2. Julia says:

looking forward to seeing them on Monday.

9. Anne Elk says:

It took me about five minutes. I like this one!

10. Bryan Atherton says:

I also liked this puzzle

Bryan A.

11. Just a few moments

12. mittfh says:

It took me a few seconds to find a possible answer, dependent on if Richard allows a close approximation 🙂

13. I think I got it. But will have to wait until Monday to see if my abstract thinking was permissible.

14. Anonymous says:

Took about 30 seconds. I like the elegance of the solution.

15. Al says:

Took me around 99.9999 seconds.

16. DiscoveredJoys says:

Easy (thank goodness). 5 seconds.

17. I can do it using 5 9s in a couple of seconds. I’m stumped about doing it with 6 nines.

1. I can’t do it with 5. At least not in 5 seconds…

2. Anne Elk says:

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!)

3. 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)

18. Duncan says:

I’ve got the answer, and a few others that might be right too. As usual it depends what assumptions you make.

19. Eddie says:

I stumbled upon the answer after 3 minutes of scribbling.

20. Stewart says:

About 99 seconds. Found it quite easily; I must be getting better at these puzzles.

21. Scarbor Siu says:

Within 10 seconds — just a piece of cake. 😉

22. Richard C says:

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.

23. ctj says:

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.

24. paulfny says:

I solved it so fast, cause and effect was suspended and the solution came to me before I’d even read the question…

25. Barry Goddard says:

i got it in 99+(99/99) seconds

26. Icanse eone answera nd itcame tome stra ightaw ay!!
No, this is not a spoiler, but it is code. 🙂

27. Barry Goddard, premature ejaculation is a common and embarrassing problem. Go see a doctor.

28. Douglas Anderson says:

one second (assuming I am right)

29. Evan says:

I’ve seen this puzzle before. I think you’ve posted it in a “bets you always win” video.

30. Anonymous says:

2 second
3,2,1
sd

31. Phil H says:

0.1692 seconds roughly

32. 99 + (99/99).

Bah Humbug if you’re dim enough to read this far without realising that you might get spoilers.

1. John G says:

999 / 9.99

33. Paul Durrant says:

I got two ways very quickly, There are probably more.

34. 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.

35. rmb says:

Fairly simple. I guess it should have more than one answer.

36. Bill White says:

37. Becky says:

(999-99)/9

1. Eddie says:

I like this solution. Well spoiled!

38. Anonymous says:

This can be done with no 9s at all as the instructions are poorly written.

39. Hal Harris says:

Saw it immediately.

40. Bill Clinton says:

15 seconds

41. Mikhail Nitishinskiy says:

5 seconds

42. Soham Suryavanshi says:

About 3 seconds and got in second try mentally. 99/99+99