51~99

51^2
51
- 49 = (100-51)
------
= (0)2(00)
= 0200

49*49
49-25 = 24
50-49 = 1
1*1 = 1
2401

2401
+ 0200
--------
= 2601

http://cashflowco.hubpages.com/hub/...square-a-number