Answer to the Friday Puzzle…

46

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On Friday I posted this puzzle:

How can you express the number 100 using six nines and no other digits?

If you have not tried to solve it, have a go now. For everyone else the answer is after the break.

99  99/99

Did you solve it? Any other solutions?

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.

46 comments on “Answer to the Friday Puzzle…

  1. ralius18 says:

    Wait.. what? Shouldn’t there be a plus between the first two ’99’s?

  2. ChrisR says:

    I think there’s a plus sign missing in Richard’s solution
    and I’m now awaiting all the other solutions.

    I also had 99.9999 (recurring)
    and 99+99/99 and (9/9)*(9/9)+99

    and I know there were some [other] good ones

  3. Baker's Dozen says:

    You forgot the plus! What a fail.

  4. Ed Wilson says:

    (9 * 9) + 9 + 9 + 9/9

  5. Julia says:

    I got 9*9+9+9+9/9

  6. Chris says:

    No plus sign missing, it is an expression of a single number: ninety-nine and ninety-nine ninety-ninths, not 99+99/99. Simply a limitation of the medium.

  7. I Claudius says:

    11 using only +, —, * and /

    99+(99/99)=100 <This was my almost instantaneous answer
    (9+9/9)*(9+9/9)=100
    (9*9)+9+9+(9/9)=100
    99-9+9+(9/9)=100
    99*(9/9)+(9/9)=100
    [99+(9/9)]*(9/9)=100
    99+(9*9)/(9*9)=100
    (99+9/9)+(9-9)=100
    (99/9)*9+(9/9)=100
    (99+9/9)/(9/9)=100
    (999-99)/9=100

    Plus another 17 using √ and ^

    99+(9^9/9^9)=100 (i.e. 99+99/99)
    (9+√9/√9)*(9+9/9)=100
    (9+√9/√9)*(9+√9/√9)=100
    (9*9)+9+9+(√9/√9)=100
    99-9+9+(√9/√9)=100
    99+(√99/√99)=100
    99*(√9/√9)+(9/9)=100
    99*(9/9)+(√9/√9)=100
    99*(√9/√9)+(√9/√9)=100
    [99+(√9/√9)]*(9/9)=100
    [99+(9/9)]*(√9/√9)=100
    [99+(√9/√9)]*(√9/√9)=100
    (99+√9/√9)+(9-9)=100
    (99/9)*9+(√9/√9)=100
    (99+√9/√9)/(9/9)=100
    (99+9/9)/(√9/√9)=100
    (99+√9/√9)/(√9/√9)=100

  8. Eddie says:

    99+[cos(tan(sin(9)))*e^(sin(√9))]/[cos(tan(sin(9)))*e^(sin(√9))]

  9. Anita Evans says:

    (9×9)+9+9+9/9

  10. Alex says:

    99 + (99^(9-9)) = 100

  11. Furie says:

    (9×9)+9+9+(9/9)

  12. Jarty says:

    (999 – 99) / 9

  13. Dave says:

    999999 in Copeland-Bois base = 100

  14. Simon Treves says:

    Understand the problem? I don’t even understand the solutions.

  15. mgm75 says:

    As I suspected. Another nice one!

  16. michael says:

    I mis-red it, so used the number 9 rather than the digit:
    (9×9) + (9+9) + (9/9)

  17. Anne Elk says:

    Can anyone offer the solution with five nines instead, as mentioned on Friday?

  18. Eddie says:

    99+9/(√9√9) – I’m sure you’re not going to like the use of ‘√’ though.

  19. Lazy T says:

    NOON in 1.42857 secs

  20. Alan S says:

    999/999%

  21. Stan says:

    I’m shocked by how many ways there are for doing this. And I’m showing it to my grandchildren who are both very shocked and surprised.

  22. Anonymous says:

    99+99/99

  23. Tanja henney says:

    99+99/99

  24. slw says:

    I can do it in 3: 99.(9)

  25. Anonymous says:

    Oh wow, i feel stupid now.

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