Four numbers have been given, out of which three are alike in some manner and one is different. Select the number that is different.

198 165 177 132

177

198 ⇒ 1 - 9 - 8  ⇒ 1 + 8 = 9 → middle number 165 ⇒ 1 - 6 - 5  ⇒ 1 + 5 = 6 → middle number 177 ⇒ 1 - 7 - 7  ⇒ 1 + 7 = 8 ≠ 7( middle number) 132  ⇒ 1 - 3 - 2  ⇒ 1 + 2 = 3 → middle number