Actually we don't have to guess. The years are counted out.
You can follow it all the way through.
Luke 3:23; When He began His ministry, Jesus Himself was about thirty years of age, being, as was supposed, the son of Joseph, the son of Eli,
Luke 3:24; the son of Matthat, the son of Levi, the son of Melchi, the son of Jannai, the son of Joseph,
Luke 3:25; the son of Mattathias, the son of Amos, the son of Nahum, the son of Hesli, the son of Naggai,
Luke 3:26; the son of Maath, the son of Mattathias, the son of Semein, the son of Josech, the son of Joda,
Luke 3:27; the son of Joanan, the son of Rhesa, the son of Zerubbabel, the son of Shealtiel, the son of Neri,
Luke 3:28; the son of Melchi, the son of Addi, the son of Cosam, the son of Elmadam, the son of Er,
Luke 3:29; the son of Joshua, the son of Eliezer, the son of Jorim, the son of Matthat, the son of Levi,
Luke 3:30; the son of Simeon, the son of Judah, the son of Joseph, the son of Jonam, the son of Eliakim,
Luke 3:31; the son of Melea, the son of Menna, the son of Mattatha, the son of Nathan, the son of David,
Luke 3:32; the son of Jesse, the son of Obed, the son of Boaz, the son of Salmon, the son of Nahshon,
Luke 3:33; the son of Amminadab, the son of Admin, the son of Ram, the son of Hezron, the son of Perez, the son of Judah,
Luke 3:34; the son of Jacob, the son of Isaac, the son of Abraham, the son of Terah, the son of Nahor,
Luke 3:35; the son of Serug, the son of Reu, the son of Peleg, the son of Heber, the son of Shelah,
Luke 3:36; the son of Cainan, the son of Arphaxad, the son of Shem, the son of Noah, the son of Lamech,
Luke 3:37; the son of Methuselah, the son of Enoch, the son of Jared, the son of Mahalaleel, the son of Cainan,
Luke 3:38; the son of Enosh, the son of Seth, the son of Adam, the son of God.
Gen 5:5 So all the days that Adam lived were nine hundred and thirty years, and he died.
Gen 5:8 So all the days of Seth were nine hundred and twelve years, and he died.
Now obviously you have to figure how old Adam was when Seth was born.
Gen 5:3; When Adam had lived one hundred and thirty years, he became the father of a son in his own likeness, according to his image, and named him Seth.
Gen 5:4; Then the days of Adam after he became the father of Seth were eight hundred years, and he had other sons and daughters.
Gen 5:6; Seth lived one hundred and five years, and became the father of Enosh.
Gen 5:9; Enosh lived ninety years, and became the father of Kenan.
Gen 5:10; Then Enosh lived eight hundred and fifteen years after he became the father of Kenan, and he had other sons and daughters.
Gen 5:11; So all the days of Enosh were nine hundred and five years, and he died.
We know exactly how many years were between Adam and Abraham according to the Bible.
We know exactly how many years were between Abraham and David.
Gen 21:5; Now Abraham was one hundred years old when his son Isaac was born to him.
Gen 25:7 These are all the years of Abraham's life that he lived, one hundred and seventy-five years.
Gal 3:17; What I am saying is this: the Law, which came four hundred and thirty years later, does not invalidate a covenant previously ratified by God, so as to nullify the promise.
There were 430 years between Abrahams's promise and Moses receiving the Law
There are dates, years and hints all through the Bible. There is no where you actually have to guess. This is well documented on many Bible sites.
It isn't always quite this obvious.. sometimes someone was born 10 years after a certain person became King. That same person died 32 years after the
king lost his kingdom. But it's all there.
Gen 5:5; So all the days that Adam lived were nine hundred and thirty years, and he died.
Gen 5:8; So all the days of Seth were nine hundred and twelve years, and he died.
Gen 5:11; So all the days of Enosh were nine hundred and five years, and he died.
Gen 5:14; So all the days of Kenan were nine hundred and ten years, and he died.
Gen 5:17; So all the days of Mahalalel were eight hundred and ninety-five years, and he died.
Gen 5:20; So all the days of Jared were nine hundred and sixty-two years, and he died.
Gen 5:27; So all the days of Methuselah were nine hundred and sixty-nine years, and he died.
Gen 5:31; So all the days of Lamech were seven hundred and seventy-seven years, and he died.
Gen 9:29; So all the days of Noah were nine hundred and fifty years, and he died.
Gen 11:32; The days of Terah were two hundred and five years; and Terah died in Haran.
Gen 25:17; These are the years of the life of Ishmael, one hundred and thirty-seven years; and he breathed his last and died, and was gathered to his people.
Gen 50:26; So Joseph died at the age of one hundred and ten years; and he was embalmed and placed in a coffin in Egypt.
The Bible also tells us how old each one of these people were when their son was born.
Gen 5:3; When Adam had lived one hundred and thirty years, he became the father of a son in his own likeness, according to his image, and named him Seth.
Gen 5:4; Then the days of Adam after he became the father of Seth were eight hundred years, and he had other sons and daughters.
Gen 5:6; Seth lived one hundred and five years, and became the father of Enosh.
Gen 5:7; Then Seth lived eight hundred and seven years after he became the father of Enosh, and he had other sons and daughters.
Gen 5:9; Enosh lived ninety years, and became the father of Kenan.
Gen 5:10; Then Enosh lived eight hundred and fifteen years after he became the father of Kenan, and he had other sons and daughters.
Gen 5:12; Kenan lived seventy years, and became the father of Mahalalel.
Gen 5:13; Then Kenan lived eight hundred and forty years after he became the father of Mahalalel, and he had other sons and daughters.
Gen 5:15; Mahalalel lived sixty-five years, and became the father of Jared.
Gen 5:16; Then Mahalalel lived eight hundred and thirty years after he became the father of Jared, and he had other sons and daughters.
Gen 5:18; Jared lived one hundred and sixty-two years, and became the father of Enoch.
Gen 5:19; Then Jared lived eight hundred years after he became the father of Enoch, and he had other sons and daughters.
Gen 5:21; Enoch lived sixty-five years, and became the father of Methuselah.
Gen 5:22; Then Enoch walked with God three hundred years after he became the father of Methuselah, and he had other sons and daughters.
Gen 5:25; Methuselah lived one hundred and eighty-seven years, and became the father of Lamech.
Gen 5:26; Then Methuselah lived seven hundred and eighty-two years after he became the father of Lamech, and he had other sons and daughters.
Gen 5:28; Lamech lived one hundred and eighty-two years, and became the father of a son.
Gen 5:30; Then Lamech lived five hundred and ninety-five years after he became the father of Noah, and he had other sons and daughters.
Gen 5:32; Noah was five hundred years old, and Noah became the father of Shem, Ham, and Japheth.
Gen 11:11; and Shem lived five hundred years after he became the father of Arpachshad, and he had other sons and daughters.
Gen 11:12; Arpachshad lived thirty-five years, and became the father of Shelah;
Gen 11:13; and Arpachshad lived four hundred and three years after he became the father of Shelah, and he had other sons and daughters.
Gen 11:14; Shelah lived thirty years, and became the father of Eber;
Gen 11:15; and Shelah lived four hundred and three years after he became the father of Eber, and he had other sons and daughters.
Gen 11:16; Eber lived thirty-four years, and became the father of Peleg;
Gen 11:17; and Eber lived four hundred and thirty years after he became the father of Peleg, and he had other sons and daughters.
Gen 11:18; Peleg lived thirty years, and became the father of Reu;
Gen 11:19; and Peleg lived two hundred and nine years after he became the father of Reu, and he had other sons and daughters.
Gen 11:20; Reu lived thirty-two years, and became the father of Serug;
Gen 11:21; and Reu lived two hundred and seven years after he became the father of Serug, and he had other sons and daughters.
Gen 11:22; Serug lived thirty years, and became the father of Nahor;
Gen 11:23; and Serug lived two hundred years after he became the father of Nahor, and he had other sons and daughters.
Gen 11:24; Nahor lived twenty-nine years, and became the father of Terah;
Gen 11:25; and Nahor lived one hundred and nineteen years after he became the father of Terah, and he had other sons and daughters.
Gen 11:26; Terah lived seventy years, and became the father of Abram, Nahor and Haran.
The rest gets a little harder, but it's there if you know where to look.
Gen 47:28; Jacob lived in the land of Egypt seventeen years; so the length of Jacob's life was one hundred and forty-seven years.
Gen 50:26; So Joseph died at the age of one hundred and ten years; and he was embalmed and placed in a coffin in Egypt.
2 Sam 5:4; David was thirty years old when he became king, and he reigned forty years.