multiply extremely large numbers

Hello Experts,

I am trying to find a way to multiply EXTREMELY large numbers( answers with more than a million numbers ) the answer should be written into an txt file. VB itself can only calculate small numbers or else it will start with things like: E+54 .

i found some source code on planet source code but it's maximum was about 150 numbers.

Greets Erik
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My suggestion , dont use VB for this
Richie_SimonettiIT OperationsCommented:
You only could store until double values in a variable, and the result should be a double too. It hasen't to do on how much digits but how large is the number you are trying to manage.
Richie_SimonettiIT OperationsCommented:
See this:

Double data type
A data type that holds double-precision floating-point numbers as 64-bit numbers in the range -1.79769313486231E308 to -4.94065645841247E-324 for negative values; 4.94065645841247E-324 to 1.79769313486232E308 for positive values. The number sign (#) type-declaration character represents the Double in Visual Basic.
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"more than a million numbers"
maybe I read this question incorrectly but I'm assuming he meant a million places in the number in which you would never want to use vb in any form or fashion to do this. Those are really LARGE numbers.
Here is an sort of answer, it works for numbers that I check using a calculator anything larger will have to be checked by hand.

create a project with 3 textboxes and a command button, copy this into the onclick of the command button

Private Sub Command1_Click()

If Len(Text2.Text) > Len(Text1.Text) Then
    num1 = Text1.Text
    num2 = Text2.Text
    num1 = Text2.Text
    num2 = Text1.Text
End If

For a = Len(num1) To 1 Step -1
  rNum1 = CInt(Mid(num1, a, 1))
  For b = Len(num2) To 1 Step -1
    rNum2 = CInt(Mid(num2, b, 1))
    result = (rNum1 * rNum2) + remainder
    tmpAns = result Mod 10
    remainder = (result - (result Mod 10)) / 10
    tStrAns = Trim(Str(tmpAns)) & num4
    num4 = tStrAns
  Next b
  If remainder > 0 Then
    num4 = Trim(Str(remainder)) & num4
  End If
  num4 = num4 & String(Len(num1) - a, "0")
  num3 = Text3.Text
  remainder = 0
  Select Case Len(num3) - Len(num4)
    Case Is < 0
      ans1 = String(Len(num4) - Len(num3), "0") & num3
      ans2 = num4
    Case Is = 0
      ans1 = num3
      ans2 = num4
    Case Is > 0
      ans1 = num3
      ans2 = String(Len(num3) - Len(num4), "0") & num4
  End Select
  For c = Len(ans1) To 1 Step -1
    aNum1 = CInt(Mid(ans1, c, 1))
    aNum2 = CInt(Mid(ans2, c, 1))
    result = (aNum1 + aNum2) + remainder
    tmpAns = result Mod 10
    remainder = (result - (result Mod 10)) / 10
    tStrAns = Trim(Str(tmpAns)) & StringAns
    StringAns = tStrAns
  Next c
  If remainder > 0 Then
    StringAns = Trim(Str(remainder)) & StringAns
  End If

  Text3.Text = StringAns: StringAns = "": num4 = "": remainder = 0
Next a
MsgBox "Done"

End Sub

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WarLordAuthor Commented:

you program works but when i take very large numbers i get an type mismatch
Where does the mismatch occur?
No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:

Answered Hornet241
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Visual Basic Classic

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