27 math tests

[GabrijelAB]

Task

@HrvojeJuric

Adds #27.

Description

Added tests form Business math logic, removed redundant methods and changed operator overwrites with actual methods.

Testing

Tests were added.

Documentation

No documentation

[GabrijelAB]

Ja sam bacio oko puno puta, i izgledalo mi je da sve ima smisla, al bi htio da i ti provedeš par minuta gledajući kak to sve izgleda !!