Cannot download .xls from web to iPad

Its not a download process per se. Click on the link to the document and allow it to open in Safari. Once it opens, tap the screen and you should see a button on the upper right for opening the file in Numbers.

Safari doesn't support downloading files in the traditional manner. there's an app called ReaddleDocs that has a browser and supports downloading and 'send to' but no idea if it works with numbers....and it's a paid app so not a free experiment.

the other alternative is to download that excel file on a computer, then mail it to the iPad and utilize the 'send to' part of the mail app to get it into numbers.

Actually, as stated above, if you have Numbers installed, all you have to do is open the file in Safari, then open in Numbers. From ther you can save it to Numbers sandbox. Another app isn't needed.