Google Sheets – How to Use Google Spreadsheets to Post to a Web Service

If you have row array with your values you can use this custom function to calculate the sum of the numbers (you can't use REGEXEXTRACT in the Script Editor, instead you have to use the JavaScript's RegExp function):

function sumLoop(v) {
  var sum = 0;

  for (var c = 0; c < v[0].length; c++) {
    var pattern = new RegExp("\\d+", "gi");  
    sum += parseFloat(pattern.exec(v[0][c]));
  } 

  return sum;
}​

For some reason if in the above function we'll ask for the number of rows (v.length as they mention in Google Forums), it returns an error.

So in order to see it action do the following, after copying the above function in the Script Editor:

+---+-----------+----------+----------+-----------------+
|   | A         |  B       | C        | D               |
+---+-----------+----------+----------+-----------------+
| 1 | Foo (100) | Bar (30) | Baz (50) | =sumLoop(A1:C1) |
+---+-----------+----------+----------+-----------------+

At this time it's not possible because Google Docs doesn't have built-in features to embed external content.

There are features to insert external content like the Insert menu, the Research tool, and add-ons but they are not able to "link" content. The insert an image, insert a drawing, insert a copy of the selected content; the research tool could insert link to a web page, a copy of text or of a image, but not to embed them in the way that an IFRAME works in a webpage or a gadget/widget in a web page or a sharing tool like Google+ among others.

References from the Google Docs Help Center
Insert an image
Insert a drawing
Research tool