What set of numbers does 0.25 belong?

Answer 1

To any set that contains it!

It belongs to {0.25},

or {45, sqrt(2), pi, -3/7, 0.25},

or multiples of 0.05,

or fractions between 0 and 1,

or reciprocals,

or rational numbers,

or real numbers,

or complex numbers,

etc.