Probably anywhere from between a handful to 400 words, depending on the text size and number of words.
Do you have any good legal information in either Spanish or English on paper that you would like to transfer to your digital collection? A digital camera may be your solution. It is portable and can capture images much faster than most scanners.
Here are some excellent tips from ABBYY FineReader. Just remember to keep the information for yourself and not to violate any copyright laws.