# Solving problems with the floor function

I've got the following problem:

If I want to calculate the following equation,

S[EK_] = Floor[Piecewise[{{0, 0 < EK < 8130},
{((933.70*((Floor[EK] - 8130)/10000) + 1400)*(Floor[EK] - 8130)/
10000), 8130 < EK <=
13469}, {((228.74*((Floor[EK] - 13469)/10000) +
2397)*((Floor[EK] - 13469)/10000) + 1014),
13469 < EK <= 52881},
{(0.42*Floor[EK] - 8196), 52881 < EK <= 250730},
{(0.45*Floor[EK] - 15718), 250730 < EK}}]]

Solve[S[x]/x == 0.25, x]


Mathematica is calculating but cannot solve the equation. The same goes for another set of equations.

Does anybody see the error in the equation or the function?

Beste wishes

It is best to provide exact numbers for Solve. This works (just a reminder, more often than not you should use S[EK_]:=... for function definitions, see e.g.: What is the difference between Set and SetDelayed?):
Solve[S[x]/x == 0.25 // Rationalize, x]