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I am struggling with a Project Euler problem with Mathematica, what I want to do is to Replace a list like this {5,6,x,x,3} with the rule {x -> i} to {5,6,0,0,3}, {5,6,1,1,3}etc,and here is my code:

countP[l_list] := Select[
FromDigits /@ Table[Evaluate[l /. {x -> i}], {i, 0, 9}], PrimeQ] //

countP[{5, 6, x, x, 3}]

it turns out not working.but when I try the code below,

FromDigits /@ Table[{5, 6, x, x, 3} /. {x -> i}, {i, 0, 9}], 
PrimeQ] // Length

It works, and return a value 7 What's wrong with the first code? and how can I deal with it ?

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closed as too localized by m_goldberg, Sjoerd C. de Vries, Michael E2, rm -rf May 4 '13 at 15:57

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It should be l_List. Capitalization matters. –  J. M. May 4 '13 at 1:26
Thank you so much, It works. –  tintin May 4 '13 at 1:30
You should be allowed to answer your own question in a few hours... –  J. M. May 4 '13 at 2:49
btw, your table generation can be made slightly more compact, Table[{5, 6, i, i, 3}, {i, 0, 9}], or {5, 6, #, #, 3} & /@ Range[0, 9] –  Aky May 4 '13 at 3:57
Thanks,I'll try that. –  tintin May 4 '13 at 9:39

1 Answer 1

I just got a little mistake with my code. The countP[l_list] should be :

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