lowest common denominator

noun2

1. •
   The smallest positive integer which is a multiple of every denominator of several fractions.

   • The lowest common denominator of ¹⁄₆ and ³⁄₁₀ is 30.
2. •
   (figurative) The simplest or base shared interest or characteristic among a group or collection of people etc.

   • Reality TV really is appealing to the lowest common denominator in audiences.