Bookfinder.com is a good place to view what other people are asking for similar books. This is not the same as knowing what similar books have sold for, but it puts you in the range of value --unless your book is so rare that nothing like it can be found for sale.
You can find information about the value and history of an old coin with a cross on it by consulting numismatic books, visiting coin dealers or collectors, or researching online on websites like Numista or the American Numismatic Association.
Most Libraries will have such books
Old books about basic programming can be found in libraries. One will find many good old books for programming in libraries of colleges or universities.
Old chicago
how much for 100yr old ART BOOKS WITH INK DRAWING
The three books in the old testament of historical value are the book of Esther, Ezra and Book of Songs.
Some books
It depends on the particular book you have and their conditions, try searching for their titles on Abe.com or Alibris.com to find out if they have any value.
Most old Encyclopedia sets have little value, because the content is out of date. But you could try a used books dealer.
There are many online guides availble to use. You could also take it to a collector or antique shop.
Find a dealer.
To find the percentage of change, subtract the old value from the new value to determine the change. Then, divide the change by the old value. Finally, multiply the result by 100 to convert it to a percentage. The formula can be summarized as: ((\text{New Value} - \text{Old Value}) / \text{Old Value} \times 100).