The word(s) "three" appears 30 time(s) in 27 verse(s) in Quran in Mohsin Khan translation.

(11) And in the earth are neighbouring tracts, and gardens of vines, and green crops (fields), and date-palms, growing into two or three from a single stem root, or otherwise (one stem root for every palm), watered with the same water; yet some of them We make more excellent than others to eat. Verily, in these things there are Ayat (proofs, evidence, lessons, signs) for the people who understand.

(12) (Some) say they were three, the dog being the fourth among them; and (others) say they were five, the dog being the sixth, - guessing at the unseen; (yet others) say they were seven, and the dog being the eighth. Say (O Muhammad صلى الله عليه وسلم): "My Lord knows best their number; none knows them but a few." So debate not (about their number) except with the clear proof (which We have revealed to you). And consult not any of them (people of the Scripture - Jews and Christians) about (the affair of) the people of the Cave.

(13) And they stayed in their Cave three hundred (solar) years, adding nine (for lunar years). (Tafsir Al-Qurtubi)

(14) [Zakariyya (Zachariah)] said: "My Lord! Appoint for me a sign." He said: "Your sign is that you shall not speak unto mankind for three nights, though having no bodily defect."

(15) For every nation We have ordained religious ceremonies [e.g. slaughtering of the cattle during the three days of stay at Mina (Makkah) during the Hajj (pilgrimage)] which they must follow; so let them (the pagans) not dispute with you on the matter (i.e. to eat of the cattle which you slaughter, and not to eat of the cattle which Allah kills by its natural death), but invite them to your Lord. Verily you (O Muhammad صلى الله عليه وسلم) indeed are on the (true) straight guidance (i.e. the true religion of Islamic Monotheism).

(16) O you who believe! Let your slaves and slave-girls, and those among you who have not come to the age of puberty ask your permission (before they come to your presence) on three occasions: before Fajr (morning) Salat (prayer), and while you put off your clothes for the noonday (rest), and after the 'Isha' (late-night) Salat (prayer). (These) three times are of privacy for you; other than these times there is no sin on you or on them to move about, attending to each other. Thus Allah makes clear the Ayat (the Verses of this Qur'an, showing proofs for the legal aspects of permission for visits) to you. And Allah is All-Knowing, All-Wise.

(17) Within three to nine years. The decision of the matter, before and after (these events) is only with Allah, (before the defeat of the Romans by the Persians, and after the defeat of the Persians by the Romans). And on that Day, the believers (i.e. Muslims) will rejoice (at the victory given by Allah to the Romans against the Persians) -

(18) All the praises and thanks be to Allah, the (only) Originator [or the (Only) Creator] of the heavens and the earth, Who made the angels messengers with wings, two or three or four. He increases in creation what He wills. Verily, Allah is Able to do all things.

(19) He created you (all) from a single person (Adam); then made from him his wife [Hawwa' (Eve)]. And He has sent down for you of cattle eight pairs (of the sheep, two, male and female; of the goats, two, male and female; of the oxen, two, male and female; and of the camels, two, male and female). He creates you in the wombs of your mothers: creation after creation in three veils of darkness. Such is Allah your Lord. His is the kingdom. La ilaha illa Huwa (none has the right to be worshipped but He). How then are you turned away?

(20) And (remember) when We sent towards you (Muhammad صلى الله عليه وسلم) a group (three to ten persons) of the jinn, (quietly) listening to the Qur'an. When they stood in the presence thereof, they said: "Listen in silence!" And when it was finished, they returned to their people, as warners.