Finding number such as 111111,0000,4444, using REPLICATE
columnname = REPLICATE(LEFT(columnname,1),LEN(columnname))

E.g.   

columnname = '111111' 
=&gt;  
LEFT(columnname,1) = '1'
LEN(columnname)    = 6

REPLICATE(LEFT(columnname,1),LEN(columnname)) = 
REPLICATE(        '1'       ,       6       ) = 
'111111'


You take the leftmost character of the column and replicate it to the length of the column.
If the result is equal to the column then you know that all the characters of the column are the same of the leftmost character.