What is the age of the earth according to the Bible?

The scriptures make no mention of the Earth's age, since the Earth itself was already created (to some extent) before the first creative "Day" had begun. (Genesis 1:1-5) Most likely it had been there for millions or even billions of years before Jehovah God began to do any kind of alterations to it.

(New World Translations of the Holy Scriptures)