You will need the following website: http://www.string-functions.com/hex-string.aspx
This has the option to convert hes to text and vice versa but you need to click a link to toggle between the two.
Here is your homework: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 me your HEX reply to ahd@brynelian.conwy.sch.uk
Remember: When logging in to www.gmail.com at home, you need to enter
your full email address i.e. logon_name@students.brynelian.conwy.sch.uk
Good luck!