Welcome paul The difficulty in calculating percentiles usually comes from compensating the unknowns, from putting values in & # 39; cubes & # 39; or to massage the values so that it makes sense in a particular statistical distribution. You do not have any of that!
Your "percentile" means "what fraction was below me?" in this context. With 853 runners, 853 minus 72 were for you. Doing the math, that means that 781 of the 853 competitors came after you. Then your percentile is 781 divided by 853.
In the form of leaves; says you Placement is in A2 and its total Competitors account is in B2. To put your percentile in C2, enter:
= (B2-A2) / B2
Or do it all in one cell,
= 1-72 / 853
This will show you a number from 0.00 to 1.00, which can then be displayed as a percentage with the% button in the Sheets menus.