Restklassen u.s.w.

Remove["Global`*"]

{Quotient[56789, 1234]*1234, Mod[56789, 1234]}

Quotient[56789, 1234]*1234 + Mod[56789, 1234]

(56789/1234)*1234 == 
      Quotient[56789, 1234]*1234 + Mod[56789, 1234]