Viktiga begrepp
N) Naturliga tal (nollan med)
0,1,2,3,4, ... 123, ... ( positionssystemet)
Z) Heltal
..., -3, -2, -1, 0, 1, 2, 3, ...
Q) Bråk
..., -1/1, ...., 0, ... ,1/1, ..., 2/1
0, , ...,1/4, ...,1/2, , ...,3/4, ...
R) Reella tal
..., 3, .. pi, ..., 4,
> (real? pi)
By Edward Krogius