string.PatternSafe
Example
Replaces all occurrences of "100%" in a string with "0%" and prints it.
We call string.PatternSafe here as '%' is a special character when used in Lua patterns.
local result = string.gsub( "You scored 100%!",
string.PatternSafe( "100%" ),
string.PatternSafe( "0%" ) )
print( result )
Output: You scored 0%!