" 
  it should be as accessible as possible, which in this case means to highschoolers as the topic is not too advanced for them, and the first two proofs in particular are accessible to anyone that's encountered repeating decimals as they otherwise use only basic arithmetic. See e.g. MOS:MATH#Article introduction: ""The lead should as far as possible be accessible to a general reader, so specialized terminology and symbols should be avoided as much as possible"". "