The seat map is a grid

A seat number like 14C is a coordinate: the row, then a letter for the place across. In a cabin with six seats a row, A to F with the aisle between C and D, the letters at the ends (A and F) are windows and the letters beside the aisle (C and D) are aisles. So 14C is an aisle seat on the left side, fourteen rows back.

Because it is a grid, counting is multiplication. Thirty rows of six is 180 seats, and every row has two windows, so thirty rows hold 60 window seats. Children on ArrayPals find a seat on a small cabin, then count a whole cabin without counting every seat.