Excel file, replace special character single quotes which besides numbers

I have work with spreadsheet gem on ruby, Sometime I do realize that in the LibreOffice, the content is something like '24%, the character single quote refers to a string. However, I want a number instead. A possible way to convert them without programming is Find and Replace. However it does not easy as I say because the character ' is a special character in LibreOffice, you have to use regular expression to work with this.

There is a solution to convert string to number in such case is using replace function name Find and Replace C-h in LibreOffice. In the Search for text, type ^.; in the Replace with, type $. In the other options, please tick on Regular expressions. Finally, you can choose replace or replace all.