The number 24 is equal to (four factorial).
A number puzzle asks to construct 24 in as many ways possible using elementary mathematical operations on three copies of the same digit. Example solutions include
(1)
 
(2)
 
(3)
 
(4)
 
(5)
 
(6)
 
(7)
 
(8)
 
(9)

where the not necessarily elementary "operation" of digit concatenation has been indicated using the symbol , any solution with 2 can be replaced with the trivial substitution , and all occurrences of and can be replaced by , , , , etc.