Calculate time complexity of modular arithmetic

I wanted to calculate What is the time complexity of this? I'm using a Java program?

Can anyone provide an explanation of the time complexity for the following calculations?
c= a * b mod n

and

m = a ^-1 * b mod n

I need any suggest.

Provided you are using standard data types (not something like arbitrarily big integers), then these calculations are done in constant time.

thank you for replay
Are you means constant time is O(1) or O(n)

if my variable has 256 bits
whats time complexity?

I waiting for you?!!!!!!!!!!!!!!!!!!!!!!!