数字小于20的正方形数字板

1^2=1

2^2=4

3^2=9

4^2=16

5^2=25

6^2=36

7^2=49

8^2=64

9^2=81

10^2=100

11^2=121

12^2=144

13^2=169

14^2=196

15^2=225

16^2=256

17^2=289

18^2=324

19^2=361

20^2=400