The first is easy enough, if you understand alternate bases. Many kids don't and I'm not sure that it's worth spending much time on besides a real quick, 20-minute "check this out" session.
"Base eight is just like base ten ... if you're missing two fingers." - Tom Lehrer. (What? can't handle 30-50 year old cultural references?)
Standard instructions for this series: No calculator allowed. Express answers in reduced form. Rationalize denominators. Radicals must be reduced. All numbers are base ten unless otherwise specified. Do not approximate radicals or π. Leave such answers as 1025π or √39, for example. Source: UVM Math Contest 2013
answer 07, answer 08.