Answer:
884,375
Step-by-step explanation:
The first digit can't be 0, so there are 9×10⁵ = 900,000 possible six-digit numbers.
Of those, the number of six-digit numbers that have only odd digits is 5⁶ = 15,625.
Numbers with at least one even digit are all numbers that don't have only odd digits. So the number of six-digit numbers with at least one even digit is:
900,000 − 15,625 = 884,375