77 - 77 = 0

77 : 77 = 1

7 : 7 + 7 : 7 = 2

(7 + 7 + 7) : 7 = 3

77 : 7 - 7 = 4

7 - (7 + 7) : 7 = 5

(7 x 7 - 7) : 7 = 6

√(7 x 7) + 7 - 7 = 7

(7 x 7 + 7) : 7 = 8

(7 + 7) : 7 + 7 = 9