Question

How to calculate sum of series 1 + 11 + 111 + 1111 + ... N in VB.NET

Answer 1

Imports System

' sum = 1 + 11 + 111 + 1111 + ... N 

Public Class Program
    Public Shared Function sum_of_series(ByVal N As Integer) As Integer
        Dim sum As Integer = 0
        Dim tmp As Integer = 1

        For i As Integer = 0 To N - 1
            Console.Write(tmp & " ")

            If i < N - 1 Then
                Console.Write("+ ")
            End If

            sum += tmp
            tmp = (tmp * 10) + 1
        Next

        Return sum
    End Function

    Public Shared Sub Main(ByVal args As String())
        Dim N As Integer = 6
	
        Dim sum As Integer = sum_of_series(N)
	
        Console.WriteLine("= " & sum)
    End Sub
End Class




' run:
'
' 1 + 11 + 111 + 1111 + 11111 + 111111 = 123456
'

 

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