{number} will repeat the previous element the specified number of times
^ at the start of a range will invert the range. [^0-9] matches anything that isn't a number.
parentheses make a group. hello{5} matches hellooooo. (hello){5} matches hellohellohellohellohello.
^ outside of a range will match the start of the line. $ will match the end of the line
Make a regular expression that matches all 3 digit numbers
Make a regular expression that matches all numbers at least 3 digits
Make a regular expression that matches all vowels
Make a regular expression that matches all consonants
Make a regular expression that matches "blablabla"