The Meaning of Numbers: The Number 30
The number 30 can symbolize dedication to a particular task or calling. Aaronic priests were dedicated to serve at 30, in part because it was the age when a person reached both physical and mental maturity and could therefore handle major responsibilities. John the Baptist, who was of priestly descent (his mother was a descendant of the daughters of Aaron and his father was a priest), began his ministry at age thirty. In the Fall of 26 A.D., at the age of thirty, Christ began to publicly preach the gospel (Luke 3:23). His ministry lasted for three and one-half years.
The number thirty can also represent the sacrificial blood of Jesus. He was betrayed by Judas for 30 silver coins, which was a fulfillment of prophecy (Zechariah 11:12). When Judas flung the 'blood money' he was paid back into the temple, the priests did not accept it as an offering but rather decided to buy a potter's field with it. Though they were not aware of it, what they did was also fulfilling prophecy (verse 13). In 30 A.D. Jesus suffered and shed His precious blood as God's sacrificial Lamb for the world's sins.
Appearances of the number thirty
The Dead Sea Scrolls were discovered in caves on the upper northwest shore of the Dead Sea started in 1947. Among all the scrolls found over the years, 30 copies of the Psalms have been identified.
The patriarchs Salah (grandson of Shem), Peleg (who lived to see the world's continents divide) and Serug (the great-grandfather of Abraham) had their first sons at the age of 30.
The prophet Ezekiel begins his book of the same name "in the 30th year" (which likely referenced his age at the time - Ezekiel 1:1). It is at this time he receives his first recorded vision from God, known as the "wheel in the middle of a wheel" or "wheel within a wheel" vision.
Abraham was promised that if God found at least thirty righteous people in Sodom and Gomorrah he would not destroy the cities (Genesis 18:30).
Thirty and the Judges of Israel
Jair, one of the Judges of Israel delineated in the Bible, had thirty sons. He was wealthy enough not only to provide each of them with their own horse to ride, but also gave each of them a city for 30 total (Judges 10:4). Ibzan, another Judge of Israel, had thirty sons and thirty daughters (Judges 12:9). Samson, a Judge of Israel from 1085 - 1065 B.C., offered a prize of thirty sheets and thirty change of garments to thirty men if they answered a riddle within a week (Judges 14:11 - 14).
How is the number 30 related to mourning?
Both the death of Aaron and Moses was mourned by the children of Israel for 30 days (Numbers 20:29, Deuteronomy 34:8).
Additional info on Biblical Meaning of 30
Joseph, a type of Jesus, was thirty years old when Egypt's Pharaoh placed him in charge over all that he ruled. King David also, when he began to reign over Israel, was thirty years old (2Samuel 5:4).
31 in Scripture
One of the Hebrew names of God is El, composed of the Hebrew letters Lamed (representing 30) and Aleph (representing 1), which totals to the number 31.
Josiah, considered the best king of Judah after Israel split into two nations, began his reign at the age of eight and ruled for 31 years (640 to 609 B.C.).
One of the most commonly occurring names in God's word is Moses, which appears in 31 books. One of most frequently mentioned women in Scripture is Rebekah (Isaac's wife), whose name appears 31 times. The book of Luke contains materials from 31 Old Testament books, the second highest in the New Testament.