This site above will clear your mind.
:nth-child(6) = 6
:nth-child(n+6) = 6 7 8 9 . . .
:nth-child(-n+6) = 1 2 3 4 5 6
:nth-child(n+4):nth-child(-n+10) = 4 5 6 7 8 9 10
span:nth-type(2) = only span type 2nd
div:nth-type(2) = only div type 2nd
This site above will clear your mind.
:nth-child(6) = 6
:nth-child(n+6) = 6 7 8 9 . . .
:nth-child(-n+6) = 1 2 3 4 5 6
:nth-child(n+4):nth-child(-n+10) = 4 5 6 7 8 9 10
span:nth-type(2) = only span type 2nd
div:nth-type(2) = only div type 2nd