Mögliche Lösungen sind:

$(0! + 0! + 0!)! = (1 + 1 + 1)! = 3! = 6$

$3! = 3 \cdot 2 \cdot 1 = 6$ $\;\;\;$ $0! = 1$

$(1 + 1 + 1)! = 3! = 6$

$2 \cdot 2 + 2 = 6$

$3 \cdot 3 - 3 = 6$

$\sqrt{4} + \sqrt{4} + \sqrt{4} = 2 + 2 + 2 = 6$

$5 + 5 : 5 = 5 + 1 = 6$ (Punkt vor Strich)

$6 - 6 + 6 = 0 + 6 = 6$

$7 - 7 : 7 = 7 - 1 = 6$ (Punkt vor Strich)

$8 - \sqrt{\sqrt{8 + 8}} = 8 - \sqrt{4} = 8 - 2 = 6$

$\sqrt{\sqrt{16}} = \sqrt{4} = 2$

$\sqrt{9} + \sqrt{9} - \sqrt{9} = 3 + 3 + 3 =6$