1400 years ago people knew the brightest star in the night sky, Sirius, however nobody knew the distance to this star. Sirius is mentioned in the Quran by name in chapter "The Star".
Getting distance to Sirius from Google.
8.61 light-years is equivalent to 861 centi light-years. So distance to Sirius is 861 centi light-years. It turned out that between the word "Star" in the first verse and the word "Earth" in verse 32 there are 861 letters.
286099 - 285238 = 861
The word "Star" and word "Earth" are separated by 861 letters. Today we know that Sirius is 861 centi light-years away from Earth.
How could an illiterate man who lived 1400 years ago have known the distance to Sirius?
The Quran (Koran, the book of Islam) contains scientific knowledge that could not have been known 1400 years ago. It ranges from basic arithmetics to the most advanced topics in astrophysics. You are invited to go through those miracles and judge for yourself.