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A &nbsp; '''CUSIP''' &nbsp; is a nine-character alphanumeric code that identifies a North American financial security for the purposes of facilitating clearing and settlement of trades. The CUSIP was adopted as an American National Standard under Accredited Standards X9.6.


;Task:
Ensure the last digit &nbsp; (i.e., the &nbsp; ''check digit'') &nbsp; of the '''CUSIP''' code (the 1<sup>st</sup> column) is correct, against the following:
* &nbsp;  037833100   &nbsp; &nbsp; &nbsp;   Apple Incorporated       
* &nbsp;  17275R102   &nbsp; &nbsp; &nbsp;   Cisco Systems   
* &nbsp;  38259P508   &nbsp; &nbsp; &nbsp;   Google Incorporated  
* &nbsp;  594918104   &nbsp; &nbsp; &nbsp;   Microsoft Corporation   
* &nbsp;  68389X106   &nbsp; &nbsp; &nbsp;   Oracle Corporation &nbsp; (''incorrect'')
* &nbsp;  68389X105   &nbsp; &nbsp; &nbsp;   Oracle Corporation    


;Example pseudo-code below.
<syntaxhighlight lang=text>algorithm Cusip-Check-Digit(cusip) is
   Input: an 8-character CUSIP

   sum := 0
   for 1 ≤ i ≤ 8 do
      c := the ith character of cusip
      if c is a digit then
         v := numeric value of the digit c
      else if c is a letter then
         p := ordinal position of c in the alphabet (A=1, B=2...)
         v := p + 9
      else if c = "*" then
         v := 36
      else if c = "@" then
         v := 37
      else if' c = "#" then
         v := 38
      end if
      if i is even then
         v := v × 2
      end if

      sum := sum + int ( v div 10 ) + v mod 10
   repeat
   
   return (10 - (sum mod 10)) mod 10
end function</syntaxhighlight>

;See related tasks: 
* [[SEDOLs|SEDOL]]
* [[Validate_International_Securities_Identification_Number|ISIN]]
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