You might want read the post on [[Regexp Builder]] before attempting these... Here’s an example of a British Postcode: OL1 3SQ. It has the format 2 letters and a digit, space, 1 digit and two letters. The following emacs regex finds this type of postcode: `[A-Z]\\{2\\}[0-9] [0-9][A-Z]\\{2\\}` 1. Write a regex to find postcodes of the type **W1 1AA** 2. Write a regex to find postcodes of the type **RM12 4JJ** 3. Write one regex that finds all three types of postcode: OL1 3SQ, W1 1AA and RM12 4JJ 4. Write a regex that finds simple email addresses of the form [email protected] 5. Now extend the regex to find email addresses of the form [email protected] 6. Now write a general email regex that will find all properly formed email addresses 7. Google the form of an ISBN (There are two standards). Write a regex to find ISBNs 8. Write a regex that can find unnecessary white space in a line of text `This      line     has              unnecessary      white space    . |              So does this line   | This line does not.` Finally... “He said ‘Have you got the time?’” “Why didn’t he look at his watch?” Write a regex that can find the left single quotes: 'and right double quotes: " in the above conversation.