Clock description: Hour hand between 8 and 9. Minute hand one minute-mark past the 6.

One morning when you leave your house, you witness an automobile accident in your street. You look at your watch when it happens. Later that day you are invited to a party at a neighbor's house, where people are talking about the accident. Your neighbor is eager to find out what you saw of the event. She asks you: "What time did the accident happen?" You remember that it happened at the time shown on the clock as given above.

How would you answer in this situation? (Fill the blank)

"It happened ___."

Actual time shown: 8:31
Answer: "It happened 8.30."

Why did you choose to answer this way?
I thought that was the correct time