Answer:
252
Step-by-step explanation:
The number of integers from 100 to 999 is 999 - 100 +1 = 900.
Consider the number of three-digit integers that do not contain 4 as a digit.
For the hundreds digit, there are 8 possible choices (excluding 0 and 4).
For the tens digit, there are 9 possible choices (excluding 4).
For the ones digit, there are 9 possible choices (excluding 4)
Thus, there are 8 × 9 × 9 = 648 three-digit integers without a 4.
The number of three-digit integers with at least one 4 is 900 - 648 = 252.
