How can I turn off the "Numbers" application?

"Numbers" is the Mac OS counterpart to Excel. When you extract data from the Web, you can often export it into the .csv format, which is just a primitive version of Excel limited to a single worksheet. It is very easy to "save as" a .csv file into an .xls file. But, with Mac OS, when you export data into a .csv file, it actually exports it to Numbers. The interface is quite different. Is there a way to turn off Numbers so it does not automatically capture .csv data exports?