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A peculiar pandigital (Posted on 2015-12-14) Difficulty: 3 of 5
Find the smallest positive integer N such that a concatenation of N and 2*N is a pandigital number.

30729 has this feature, but it is not the smallest number.

No Solution Yet Submitted by Ady TZIDON    
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Solution All of them | Comment 1 of 2
starting with the smallest:

   N         2N
13485  26970
13548  27096
13845  27690
14538  29076
14685  29370
14835  29670
14853  29706
14865  29730
15486  30972
16485  32970
18546  37092
18645  37290
20679  41358
20769  41538
20793  41586
23079  46158
26709  53418
26907  53814
27069  54138
27093  54186
27309  54618
29067  58134
29073  58146
29307  58614
30729  61458
30792  61584
30927  61854
31485  62970
32079  64158
32709  65418
32907  65814
34851  69702
35148  70296
35481  70962
38145  76290
38451  76902
45138  90276
45186  90372
45381  90762
46185  92370
46851  93702
48135  96270
48351  96702
48513  97026
48516  97032
48531  97062
48615  97230
48651  97302

DefDbl A-Z
Dim crlf$


Private Sub Form_Load()
 Form1.Visible = True
 
 Text1.Text = ""
 crlf = Chr$(13) + Chr$(10)
 
 For n = 10000 To 99999
   DoEvents
   ns$ = LTrim(Str(n))
   good = 1
   For i = 2 To Len(ns)
     If InStr(ns, Mid(ns, i, 1)) < i Then good = 0: Exit For
   Next
   If good Then
     n2 = 2 * n
     checkstr$ = ns + LTrim(Str(n2))
     For i = 2 To Len(checkstr)
       If InStr(checkstr, Mid(checkstr, i, 1)) < i Then good = 0: Exit For
     Next
     If good Then
       Text1.Text = Text1.Text & ns & "  " & n2 & crlf
     End If
   End If
 Next

 Text1.Text = Text1.Text & crlf & " done"
  
End Sub


  Posted by Charlie on 2015-12-14 19:06:38
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