[RESOLVED] BigInteger substraction errors

I want to substract BigInteger value from another BigInteger value, but I´ve got the following errors:

1.'BigInteger' is a type and cannot be used as an expression.
2.Syntax error in cast operator; two arguments separated by comma are required.
3.Value of type 'System.Numerics.BigInteger' cannot be converted to 'String'.

My code:

Code:

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Option Strict On
Imports System.Numerics

Public Class Form3
    Dim number1 As BigInteger
    Dim number2 As BigInteger
    Dim result As BigInteger
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        number1 = CType(TextBox1.Text, BigInteger)
        number2 = CType(TextBox2.Text, BigInteger)
        result = CType(TextBox3.Text, BigInteger)
        result = CType(TextBox1.Text, BigInteger) - CType(Val(TextBox2.Text, BigInteger))
        TextBox3.Text = result
    End Sub
End Class

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2-why two arguments?
3-why biginteger isn´t able to handle numbers directly?

Thanks.

The second error is due to

Code:

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CType(Val(TextBox2.Text, BigInteger))

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you shouldn't have the Val bit in there.

Not sure what you mean about BigInteger not being able to handle numbers directly either.

That entire bit of code could be simplified to

Code:

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Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim number1 = CType(TextBox1.Text, BigInteger)
    Dim number2 = CType(TextBox2.Text, BigInteger)
    Dim result = number1 - number2

    TextBox3.Text = result.ToString()
End Sub

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So it seems like that it´s neccessary to declare the array alogside with biginteger type and requiered component. The other is pretty simple. Now its much more clear. Thanks a lot!