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By listing the first six prime numbers: 2, 3, 5, 7, 11, and
13, we can see that the 6^{th}
prime is 13.

What is the 10001^{st}
prime number?

Function AllPrimes(ByVal UpperVal As Variant) As Long() 'Basic implementation of the Sieve of Eratosthenes If UpperVal < 2 Then Exit Function Dim AllNbrs() As Long, Rslt() As Long ReDim AllNbrs(UpperVal - 1) Dim I As Long For I = 3 To UpperVal Step 2 AllNbrs(I - 1) = I Next I For I = LBound(AllNbrs) To UBound(AllNbrs) If AllNbrs(I) = 0 Then Else Dim J As Variant For J = CDec(AllNbrs(I)) ^ 2 - 1 To CDec(UBound(AllNbrs)) Step AllNbrs(I) AllNbrs(J) = 0 Next J End If Next I ReDim Rslt(UpperVal) Rslt(0) = 2 I = 1: J = LBound(AllNbrs) For J = LBound(AllNbrs) To UBound(AllNbrs) If AllNbrs(J) <> 0 Then Rslt(I) = AllNbrs(J): I = I + 1 Next J ReDim Preserve Rslt(I - 1) AllPrimes = Rslt End Function