Mathematics has a variety of unexpected relationships with many areas of human activity. Here we concentrate on the relationships with music and art.

• Music. One finds information on the relationship between musical intervals and rational numbers, Fourier analysis as a construction kit with which all musical tones can be assembled from simple oscillations, etc.
• Art. Mathematics often reveals an aesthetic side, for example when results are displayed graphically.
  (A well-known example is fractals.) Other points of contact between mathematics and art can be found under the heading "symmetry". Furthermore, special numbers (such as the golden ratio) play an important role.