18:2.10:9:2.7:35.1=1

18 ∶ 2 = 9
9 × 10 = 90
90 ∶ 9 = 10
10 ∶ 2 = 5
5 × 7 = 35
35 ∶ 35 = 1
1 × 1 = 1

Ответ: 1