How to indicate my grades? (British applicants)

[Steve2016]

Hello everyone. I want to ask people who did a degree in the UK about how you indicate grades on your application forms.

As you know, in UK universities 70 means first-class or A. But this is out of 100, so when you say you got 60 out of 100 it sounds like you haven't done very well although it is B. My application forms ask me to write what is the maximum mark achievable and what I got. Technically, you can get 100 but no one gets anywhere near it. I know this because I got 78 overall and I am the top of the class. Is there anyone having trouble for the same reason?   

[TakeruK]

Professors in the US know that UK grades work differently. You aren't the first nor the last person to be applying to their program from the UK. They may even have current faculty who have UK degrees. I would just follow the instructions. If there is a comment box, you may put something like "first-class" with it but it's not really necessary.