13
$\begingroup$

Add the four basic operators $\times\div+\,\;-$ and optionally brackets to:

$10 \quad 9 \quad 8 \quad 7 \quad 6 \quad 5 \quad 4 \quad 3 \quad 2 \quad 1$

To get the total $2017$.

Rules:

  • Look for the simplest solution - i.e. the least amount of characters (ignoring spaces). Please include your character count in your answer.
  • Keep the order; do not add or combine numbers.
  • Use all four operators at least once.

Credit for initial concept: Alex Bellos


Previous year: here.

$\endgroup$
6
  • $\begingroup$ Is implicit multiplication allowed? $\endgroup$ Jan 1 '17 at 12:11
  • $\begingroup$ For best solution you can mix up the numbers like 109X87+6543-21 $\endgroup$ Jan 1 '17 at 13:27
  • 8
    $\begingroup$ As of 2017 Code Golf is invading puzzling. $\endgroup$
    – Zxyrra
    Jan 1 '17 at 16:05
  • 1
    $\begingroup$ Just being curious about it: is there a known algorithm to solve it? (given inputs: list of possible numbers, desired result). I'm thinking about dynamic programing. Also don't know how I could call this problem to look for litterature. $\endgroup$
    – pltrdy
    Jan 2 '17 at 11:57
  • $\begingroup$ @pltrdy Have you read this post? $\endgroup$
    – xzczd
    Jan 5 '17 at 14:58
22
$\begingroup$

This one is 20 characters:

$10×9×8×7 \div 6 \div 5×4×3 + 2 - 1$

$\endgroup$
7
  • 6
    $\begingroup$ @Paparazzi thanks - I think I left my counting skills in 2016. $\endgroup$
    – Glorfindel
    Jan 1 '17 at 12:42
  • 8
    $\begingroup$ Will work for the next two years as well (changing the final - to a x or +) $\endgroup$ Jan 1 '17 at 15:26
  • $\begingroup$ @TomCarpenter And it would also work for 2013-2015 by flipping the sign for 2 and manipulating the operator for 1 accordingly. This should also be the shortest answer, considering it has no brackets. $\endgroup$
    – Reti43
    Jan 1 '17 at 23:54
  • $\begingroup$ I wrote a script to try all combinations without parenthesis, this is the only one it finds. $\endgroup$
    – C5H8NNaO4
    Jan 2 '17 at 2:35
  • $\begingroup$ @TomCarpenter no it would not: a - sign would be missing. $\endgroup$
    – Cœur
    Jan 2 '17 at 11:36
15
$\begingroup$

One can even find $2017$ by using only 5 numbers given in the question without changing the order as below:

$9×8×7×4+1=2017$

Here are the actual answers for the question:

  1. $(10+9×8×7-6-5)×4+3+2×1=2017$ - 22 Chars

  2. $(10×9×8×7)\div((6×5)\div(4×3))+2-1=2017$ - 28 Chars

  3. $10×9×8×7×6\div5\div(4-3+2)+1=2017$ - 22 Chars

  4. $(10+9×8×7-6-5)×4+3+2\div1=2017$ - 22 Chars

  5. $10×9×8×7\div(6+5+4)×3×2+1=2017$ - 22 Chars

  6. $10-9+8×7×6×(5-4)×3×2\div1=2017$ - 22 Chars

  7. $(10-9+8)×7×(6-5+(4-3)×2)+1=2017$ - 26 Chars

  8. $(10+9)×8×(7+6)+5+4×3×(2+1)=2017$ - 26 Chars

$\endgroup$
4
  • 2
    $\begingroup$ You can simplify some of those, considering a ÷ (b ÷ c) = a ÷ b × c and a ÷ (b × c) = a ÷ b ÷ c $\endgroup$ Jan 1 '17 at 20:35
  • 2
    $\begingroup$ #3 has mismatching brackets $\endgroup$
    – vrwim
    Jan 2 '17 at 0:49
  • $\begingroup$ Can you include the number of characters for each? $\endgroup$
    – IAmInPLS
    Jan 2 '17 at 11:17
  • $\begingroup$ @IAmInPLS fixed all errors... $\endgroup$
    – Oray
    Jan 2 '17 at 11:45
2
$\begingroup$

22 characters:

$10×9×8×7×6÷5÷(4−3+2)+1$

There may be less, but pretty happy about this

There is also:

$10×9×8×7×6÷(5+4×3−2)+1$

Which is same length but slightly different

$\endgroup$
1
$\begingroup$

(((10*9*8*7)/(6*5))*4*3)+2-1=2017

$\endgroup$
1
$\begingroup$

2017 = 10+9+8+7+6+5+4+3+2+1+987+654+321

$\endgroup$
1
  • $\begingroup$ While this is a rather interesting result, this is not an answer to the question. $\endgroup$ Jan 6 '17 at 6:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.