Geometric Progression Generator

Private Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnCalculate.Click
    Dim firstTerm As Double
    Dim commonRatio As Double
    Dim numTerms As Integer
    Dim results As New List(Of String)
    
    ' Validate inputs
    If Not Double.TryParse(txtFirstTerm.Text, firstTerm) Then
        MessageBox.Show("Please enter a valid number for first term")
        Return
    End If
    
    If Not Double.TryParse(txtCommonRatio.Text, commonRatio) Then
        MessageBox.Show("Please enter a valid number for common ratio")
        Return
    End If
    
    If Not Integer.TryParse(txtNumTerms.Text, numTerms) OrElse numTerms < 1 Then
        MessageBox.Show("Please enter a positive integer for number of terms")
        Return
    End If
    
    ' Clear previous results
    lstResults.Items.Clear()
    lstResults.Items.Add("Term".PadRight(10) & "Value")
    lstResults.Items.Add("".PadRight(20, "-"))
    
    ' Calculate and add terms
    Dim currentTerm = firstTerm
    For termIndex = 1 To numTerms
        lstResults.Items.Add($"{termIndex.ToString().PadRight(10)}{currentTerm}")
        currentTerm *= commonRatio
    Next
End Sub

function calculateGP() {
    // Get input values
    const firstTerm = parseFloat(document.getElementById('firstTerm').value);
    const commonRatio = parseFloat(document.getElementById('commonRatio').value);
    const numTerms = parseInt(document.getElementById('numTerms').value);
    
    // Validate inputs
    if (isNaN(firstTerm) {
        alert('Please enter a valid number for first term');
        return;
    }
    
    if (isNaN(commonRatio)) {
        alert('Please enter a valid number for common ratio');
        return;
    }
    
    if (isNaN(numTerms) || numTerms < 1 || numTerms > 50) {
        alert('Please enter a valid number of terms (1-50)');
        return;
    }
    
    // Generate results
    let currentTerm = firstTerm;
    let resultsHTML = '';
    let sequence = [];
    
    for (let n = 1; n <= numTerms; n++) {
        // Format calculation display
        const calcDisplay = n === 1 ? 
            `${firstTerm} × ${commonRatio}0` : 
            `${firstTerm} × ${commonRatio}${n-1}`;
        
        resultsHTML += `<tr>
            <td>${n}</td>
            <td>${currentTerm.toFixed(4)}</td>
            <td>${calcDisplay}</td>
        </tr>`;
        
        sequence.push(currentTerm.toFixed(4));
        currentTerm *= commonRatio;
    }
    
    // Display results
    document.getElementById('gpResults').innerHTML = resultsHTML;
    document.getElementById('sequenceSummary').innerHTML = sequence.join(', ');
    document.getElementById('resultContainer').style.display = 'block';
}