Inserting line breaks in your (X)HTML will be entirely ignored. Browsers reduce all blocks of whitespace in your code to a single space on the rendered page. On the up side, this is why we can indent our XHTML without regard to how we want the page to look, on the downside this means you can't add whitespace in this fashion. Also, may I ask why so many line breaks are needed? It's very likely there's a better way to solve this particular problem without the line breaks.
Technically, it is possible to accomplish something like this on the server side, and since we're dealing with form components it's unlikely that they have any purpose without a server side script to process them (non-AJAX
JS apps being the lone possible exception). In a language like C#, the line breaks could be appended in code in this way. A line break is technically composed of one carriage return (unicode character U+000D) followed by a line feed (unicode character (U+000A). As long as you understand that C# allows you to escape Unicode values as a string like so, "\u000d\u000a", then you can use any Unicode codepoints, including line breaks, in your code. 99% of the time, the best practice is to use the escaped Unicode values to render the output to the page, then copy the actual glyphs as they render on the webpage and paste them into your code. This incorporates the real non-escaped content into your page relatively easily without having to adapt your keyboard. The better news is that once you have copied those characters into your code, they're easily available in the future for you to copy from that location. However, carriage returns and line feeds are automatically converted by virtually everything except a browser into a visual line break with the result that editors simply format your HTML document.
Also, unless I miss my guess, you don't actually want 115 line breaks in the textarea. What purpose is served by including that much whitespace in the form component on the webpage? This sounds like some kind of formatting that you need in the results that are returned by the form. In that case, trying to insert the line breaks into the text area is a violation of your abstractions. You don't want a text area with all that whitespace so don't put it in. On the server side, however, you do want the form output to have that formatting, so THAT'S where you add the whitespace. You'd simply do something like this.
Code:
string modifiedTextareaOutput ="";
// insert 115 line breaks
for (whitespaceCounter = 0; whitespaceCounter < 115; whitespaceCounter++)
{
modifiedTextareaOutput += "\u000d\u000a";
}
// append the actual user input from the textarea
string actualTextareaInput = HttpContext.Current.Request["box"]; // you use the name attribute of the form component to retrieve its data
modifiedTextareaOutput += actualTextareaInput;
This allows you to keep your HTML code the way it should be while providing for the output formatting that you need to produce from the user's input.