In a cell on Sheet A, I want to display the value of a cell on Sheet B. I
know the column that it is in (R), but not the row - the row should be equal
the last row in that column which has a nonblank value.

In other words, if the first six rows of column R on Sheet B have values,
then I want to display the value of 'Sheet B'!R6.

I think I can do this using INDIRECT(something) and COUNTA('Sheet B'!R:R),
but I can't seem to fit them together in the correct manner.

Thanks!