16.

A0 has an area of one square meter. Divide it in 2 you get 2 A1, divide again you get 4 A2, once more 8 A3 and finally 16 A4.

A0 has an area of one square meter. Divide it in 2 you get 2 A1, divide again you get 4 A2, once more 8 A3 and finally 16 A4.