How to order a polynomial from grade 0 to n and vice versa

Questions
1

Dear All,
I 'm a new Mathematica user.
How can I reorder a polynomial of grade n in the variable x?
I 'd like to be able to reorder it from grade to n and vice versa.
Example:
a0+a1x+…anx^n ;
or
anx^n+……….a1x+a0

Thanks in advance for your cooperation.

2

See here.

3

Thanks a lot for your prompt reply.
I have used the command
Expand[%] // TraditionalForm

and it works perfectly.

Regards,