2 x 2 = 4

4 x 4 = 16

6 x 6 = 36

8 x 8 = 64

10 x 10 = 100

12 x 12 = 144

14 x 14 = 196

16 x 16 = 256

18 x 18 = 324

20 x 20 = 400