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| Question 123846This question is from textbook A Problem Solving Apporach To Mathematics
 :  The 14 digits of a credit card are written in the boxes shown. If the sum of any three consecutive digits is 20, what is the value of A?
 A _ 7 _ _ _ _ _ _ _ _ 7 _ 4 
This question is from textbook A Problem Solving Apporach To Mathematics
 
 Answer by solver91311(24713)
      (Show Source): 
You can put this solution on YOUR website! If any three consecutive digits sum to 20, then the digit between the 7 and the 4 must be 9.  Then the digit preceeding the 7 has to be 4, preceeding that 9, and so on.  The digits repeat in a pattern, going backwards 4, 9, 7.  Going to the 12th digit from the right, the 7 is given, the digit between that 7 and the A must be 4, and the digit represented by the A must then be 9.
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