Puzzles/POY 2009

Puzzle of the year 2009: find phrases that generate each number i.100 , making no use of

• digits other than 2 0 0 9 in sequence
•  _ and __ and _. as numbers
• letters in numeric constants (e.g. >. 200r9 for 23 is prohibited)
• literal strings
• ?. or ?

The number of words in each phrase is to be minimized. (Word count is according to #;:y ). Where there are multiple phrases for the same number with the same number of words, phrases with fewer essential characters are preferred, and if those are equal, then phrases whose values can be worked out by hand are preferred.

Solutions:

 0  /: 2009
 1  * 2009
 2  2: 009
 3  >. 2.009
 4  # 2 0 0 9
 5  #. _2 009
 6  ! # 20 0 9
 7  #. 2 0 0 _9
 8  >. ^ 2.009
 9  {: 200 9
10  <. -: 20.09
11  20 - 09
12  >: 2 + 009
13  #. 2 009
14  <. %: 200.9
15  >. %: 200.9
16  *: # 2 0 0 9
17  #. 2 00 9
18  2 * 009
19  <: <. 20.09
20  <. 20.09
21  >. 20.09
22  >: >. 20.09
23  >. 200 % 9
24  ! # 2 0 0 9
25  #. 2 0 0 9
26  +: #. 2 009
27  #.~ 2 009
28  #. <: 20 _09
29  20 + 09
30  <: #. 20 _09
31  #. 20 _09
32  >: #. 20 _09
33  #. #.\ 2 00 9
34  #. >: 20 _09
35  <: 2 ! 009
36  2 ! 009
37  p: 2 + 009
38  #. |. 20 09
39  #. p: 2 009
40  <. +: 20.09
41  {: q: 2009
42  +: >. 20.09
43  # i: >. 20.09
44  <. %: 2009
45  2 ! _009
46  #. <: 20 09
47  p: +: #. 2 0 0 _9
48  <: #. 20 09
49  #. 20 09
50  >: #. 20 09
51  #. 20 - 0 9
52  #. >: 20 09
53  #. p: 2 00 9
54  +: #.~ 2 009
55  2 ! <: _009
56  #. |. 20 0 9
57  # , i: 2 00 9
58  +: 20 + 09
59  p: *: # 2 0 0 9
60  #. 20 >. 0 9
61  p: #. 2 00 9
62  +: #. 20 _09
63  <. o. 20.09
64  >. o. 20.09
65  >: >. o. 20.09
66  #. *: <: 2 009
67  p: 2 * 009
68  +: #. >: 20 _09
69  #. 20 + 0 9
70  <: #. 20 0 _9
71  #. 20 0 _9
72  >: #. 20 0 _9
73  p: {. 20 09
74  #. |. 2 0 0 9
75  >: #. |. 2 0 0 9
76  #. <: q: 2009
77  <: #. >: 20 0 _9
78  #. >: 20 0 _9
79  p: >. 20.09
80  +: +: {. 20 09
81  *: {: 200 9
82  #. <: 20 0 9
83  #. q: 2009
84  >: #. q: 2009
85  +/ *: 2 009
86  #. <: *: 2 009
87  <: <: #. 20 0 9
88  <: #. 20 0 9
89  #. 20 0 9
90  >: #. 20 0 9
91  >: >: #. 20 0 9
92  #. >: *: 2 009
93  >: #. >: *: 2 009
94  <: #. #.\. 2 00 9
95  #. #.\. 2 00 9
96  #. >: 20 0 9
97  #. *: 2 00 9
98  +: #. 20 09
99  <: <. -: 200.9

See also

• Puzzle of the Year 1996
  
• Puzzle of the Year 2005
  
• Puzzle of the Year 2006
  
• Puzzle of the Year 2007
  
• Puzzle of the Year 2008
  
• Puzzle of the Year 2009
  
• Puzzle of the Year 2010
  

Discussion

• Would you consider it cheating if I tried to solve this puzzle automatically by generating lots of short phrases and running them? B Jonas
• Is returning a non-atom noun with a single element equal to 2009 ok? The current entry for 0 is /: 2009, so it seems it is, but it would be better if this was explicit. If so, is it allowed to return a number that's only tolerantly equal to the goal, or a string that looks like it, etc? By the way, is _: allowed? B Jonas