.NET skulle behöva smarte kod än detta..

int iCount = 100;

        string sHtml = "<table cellpadding='0' cellspacing='0' border='0'>";

        for (int i = 1; i < iCount + 1; i++)
        {
            if (i == 1 || i == 21 || i == 41 || i == 61)
                sHtml += "<tr>";

            sHtml += "<td>";
            sHtml += "<img src='http://lorempixel.com/100/100/people/' style='margin-top:-3px'>";
            sHtml += "</td>";

            if (i == 20 || i == 40 || i == 60)
                sHtml += "</tr>";
        }
        sHtml += "</table>";

        LiteralImageGrid.Text = sHtml;

int iCount = 100;

        string sHtml = "<table cellpadding='0' cellspacing='0' border='0'>";

        for (int i = 1; i < iCount + 1; i++)
        {
            if (((i-1) % 20) == 0)
                sHtml += "<tr>";

            sHtml += "<td>";
            sHtml += "<img src='http://lorempixel.com/100/100/people/' style='margin-top:-3px'>";
            sHtml += "</td>";

            if (i % 20 == 0 )
                sHtml += "</tr>";
        }
        sHtml += "</table>";

        LiteralImageGrid.Text = sHtml;

        protected string imageTable()
        {
            int imagesTotal = 100;
            int imagesPerRow = 20;

            StringBuilder htmlTable = new StringBuilder();

            htmlTable.Append("<table>");
            int imageCount = 0;
            while (imageCount < imagesTotal)
            {
                htmlTable.Append("<tr>");
                for (int cell = 0; cell < imagesPerRow; cell++)
                {
                    if (imageCount == imagesTotal)
                    {
                        break;
                    }
                    htmlTable.Append("<td>");
                    htmlTable.Append("<img src=\"http://lorempixel.com/100/100/people/\"/>");
                    htmlTable.Append("</td>");
                    imageCount++;
                }
                htmlTable.Append("</tr>");
            }

            return htmlTable.ToString();
        }