Seven, among all the numbers, plays a significant role in Revelation. Based on the originally inspired division and order of books, it is the 49th (7 times 7) and last book of the Bible. It is also the seventh and last of the Bible's major divisions (it comes after the Law, the Prophets, the Psalms or Writings, the Gospels, the General Epistles and the Epistles of Paul).
Sadly, the overwhelming majority of modern translations like the NIV, NKJV, ESV and others hide the significance, especially in the book of Revelation, of numbers like seven. This is because these translations follow Jerome in their arrangement of books.
Jerome (c. 347 - 420 A.D.), a Catholic priest and theologian of the fourth century, compiled a Latin version of God's word known as the Vulgate. Although he was aware that the Eternal originally inspired a certain division and order of his books, he chooses to do something completely different. His choices make it harder to find the patterns of numbers the text was meant to reveal.
"It is astonishing that Jerome acknowledged his scriptural dishonesty in altering the original God breathed manuscript order of both the Old and New Testaments. Rather than being faithful to God and His Word, he chose to please men - the pope, the Roman Catholic Church and its clergy." (Holy Bible in Its Original Order - A Faithful Version (HBFV), second edition, page 3)
Seven is one of the most frequently used numbers in Holy writ. It symbolizes completeness and perfection. It also plays a prominent role in Revelation where it is used to denote several things. Sevens are used in reference to churches and Spirits before God's throne (Revelation 1:4), golden lampstands (1:12), stars (1:16), angels to the churches (1:20), Spirits of God (3:1), lamps of fire before God's throne (4:5), seals on a prophetic book (5:1) and the horns and eyes on the Lamb (5:6).
Seven, one of a few perfect numbers, is also used in Revelation in reference to Spirits of God sent to earth (5:6), angels who blow seven trumpets (8:2), thunders that speak (10:3) and heads on a dragon wearing seven crowns (12:3). Other manifestations of seven also crop up (8:1, 10:7, 11:13, 13:1, 15:1, 7, 17:9 - 10, 21:20). In the HBFV translation, words like prophecy, earthquake, sickle, blessed, star, worthy and thunders are used seven times or multiple thereof.
The second and third most common numbers used in the book are three (3) and twelve (12). Three, like seven, pictures completeness though to a lesser degree. It is found twelve times in the book. Twelve itself symbolizes government. The most prominent use of twelve is when it refers to the twelve tribes of Israel or the twelve stars in the crown of the Bride of Christ.
When the numbers in Revelation finally fulfill their prophetic duty, God will create a new heaven and a new earth after the final judgment. All those who are in the first resurrection will dwell in the New Jerusalem and the nations that are saved will dwell on the new earth. His great plan for all humans will then be completed.