The number 815 is a very consistent number in Lost, which is a combination of 8 and 15. Below is a list of the appearances of this number in chronological order by episode, and the number 815 in real life.

In Lost:

Season 1:

"Pilot: Part 1"-

• The plane that crashed was Oceanic Airlines Flight 815.

"Raised By Another"-

• Claire's appointment for the adoption signing was at 8:15.

"Whatever the Case May Be"-

• The safe deposit box Kate robbed was 815.

"Homecoming"-

• Charlie was trying to sell the model C-815 copier.

"Deus Ex Machina"-

• At the toy store Locke worked at, regular balls were in aisle 8, Nerf balls were in aisle 15.

"Born to Run"-

• Kate and Tom buried the time capsule on 8/15.

"Exodus: Part 1"-

• Michael and Walt's hotel room was 815.

Season 2:

"Man of Science, Man of Faith"-

• Adam Rutherford's time of death was 8:15.

"Lockdown"-

• The real Henry Gale's address was 815 Walnut Ridge Road.

Season 3:

"Flashes Before Your Eyes"-

• A delivery man was sending a package for 815.

"Greatest Hits"-

• The Looking Glass logo is a rabbit with a clock pointing to 8:15.

Season 4:

"The Beginning of the End"-

• The letters H O appear at Santa Rosa, which the numerical value is equal to 8 and 15.

"There's No Place Like Home: Parts 2 & 3"-

• Before shooting a man at Santa Rosa, Sayid asks what the time is, to which he replies 8:15.

In Real Life:

• South Korea's and India's Independence Day is 8/15. South Korea even has a soda called 815 soda.
• The Hiroshima bomb was dropped on August 6th, 1945 at 8:15 AM.
• 8/15 is a German term meaning "boring".