In how many no. between 100 and 1000 exactly one of the digits is 3?

Numbers between 100 to 1000 means from 101 to 999: Three-digit number: _ _ _.

Now as we need exactly one 3: possible combinations look like: 3 _ _, _ 3 _, _ _ 3.Overall numbers available are from 10 [0 to 9 and repetition is allowed]

Case 1: 3, _,_: For a first place, we have 1 way to fix '3' and for the remaining places, we have '9' options each: 1 * 9 * 9 = 81

Case 2: _, 3,_: For a second place we have 1 way to fix '3' and for the first place, we cannot have '0' therefore we have '8' options and for third place, we have '9' options: 8 * 1 * 9 = 72

Case 3: _, _, 3: For a third-place, we have 1 way to fix '3' and for the first place we cannot have '0' therefore we have '8' options and for the second place we have '9' options: 8 * 9 * 1 = 72

Total ways: 81 + 72 + 72 = 225

Answer D