Quote from the link:
"For example in Surah 18:25, we note some people that said:
"And they remained in their Cave (for) three hundred years, and (some) add nine"
The difference of 9 years noted between 300 and 309 years, is the difference between a solar and a lunar calendar.
However, the Quran informs believers what the new moons are for and they are not just for pilgrimage."
This is false Translation of the ayat there is no Year mentioned in arabic