Say you have an 8 member one-dimensional array called E what subscript variable would indicate the Rth positio

Question

...and how did you figure it out?

Answer 1

By Rth do you mean last?
Like the other person answered it depends on the programming lanugage, however most of the languages have arrays as indexed.
When ever you see the word Indexed that means the first value is 0. Some languages would specfiy "0 indexed based array", or "1 Indexed based array"

So if you want to figure out what the Last row is, every language should have some way to find the lenght or size of the array.
Something like, E.Length().
So this value, would be 1 less if the array is a "0 indexed based array".

Answer 2

Which language? Either 1- or 0-based subscript, then it is either E[R] or E[R - 1]