What is pop math?

as popularly understood,
Graspable by lay person,
w/o introducing much machinery.

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EG of cut-off is
Noyes Chapman's 15 puzzle
(claimed, falsely, by Sam Loyd)

Can't solve if switch the 14 and 15.

The statement is graspable by any,
...but the solution is just a bit too technical:
sign of permutations (& proof is a bit tricky;
conceptually it's just sign of permutation).

[There are other elementary questions, esp. in combinatorics and number theory,
 like twin primes or Fermat's Last Theorem,
 but those are far, far more complicated.]