Using regular expressions in Textastic (iPad)

In order to use regular expressions in Textastic:

(1) with the document you want to search open tap on the magnifying glass

(2) next tap on the settings cog until you are faced with a series of switches in a popover

(3) switch on "Regular Expressions"

(4) now you can go back and use regular expressions

(5) start by finding a number

  ([0-9])

and replacing with

  Number $1

(6) you'll of course need numerals in your document for this to work

(7) once you've performed the search you'll see a list of found items which you can replace individually or all at the same time, and the found items will also be highlighted in your document