Many people, secular and religious, of different cultures and worldviews, have attempted to calculate the age of the world. There is no agreement between them simply because it is an impossible task. Christians, Muslims, and Jews have tried to do the calculation based on a literal reading of the Bible and have come up with different times. The following shows the impossibility by focusing on the widely used Jewish version.
We do not know when it was that a Jew first thought to calculate years from creation. We do know that the talmudic rabbis knew nothing of this calendar, called anno mundi, “year (of the) world,” and that they used the Greek calendar. Scholars, such as Azariah de’ Rossi, in his The Light of the Eyes, speculate that the anno mundi may have originated at this time, around the sixth century, after the talmudic period. While this seems to be the date of its origin, it was not until fairly recently that Jews began to use it. Maimonides, for example, dated his documents with the Greek calendar in the thirteenth century. Jews adopted it recently simply because many forgot about its origin and thought it is a divine revelation to the Israelites at Mount Sinai. Other Jews accepted it because it is a “tradition, and one doesn’t question traditions.”
Jewry had good reasons for originally rejecting this calendar. There are theological, practical, and logical reasons why it is clear that the anno mundi calculation is incorrect. The anno mundi inventor calculated the years since creation by taking biblical numbers literally. He relied on imaginative non-factual midrashic speculations of dates when the Bible is unclear. He accepted traditions about time periods which were developed to teach homiletical lessons and not historical facts.
Many Jews feel that biblical time frames and dating were never meant to be taken literally. The Bible is not a history book. It is designed to teach about the existence of God and proper behavior. The world may have been created over a very long period of time, humans may not have appeared on earth until millions of years had passed, and the average life span before the flood may not have been hundreds of years as seem to be indicated by a literal reading of the Bible. When the Torah states that Adam lived for 930 years, it may have been referring to years that lasted from one lunar cycle to the next, about 29 ½ days. If the 930 “years” are divided by twelve (months), the result is 77.5 currently-calculated years, which is about the length of lives today. Even if the world was created in a single day, Adam did not die in the year 930, but 77.
The anno mundi calculation is based on Midrashim. For example, scripture states that Noah bore three sons when he was 500 years old, Shem, Ham, and Japheth. A midrash states that they were not all born in the same year, Shem was not the oldest son as the text seems to state, and he was born when his father was 502 years old. The numbering in the anno mundi is based on this midrashic birth day of Shem, which is contrary to the plain reading of the biblical text.
Another problem with using the anno mundi is that some of the time periods listed by the Bible are questionable. For example, it is possible to date the judges in the book of Judges one after the other, as the book implies, and insist, as does the anno mundi, that the period of the judges lasted over 500 years. However, it is more reasonable to suppose that some judges must have overlapped since they served in different tribes, we are unable to determine by how much, and scholars state the period was only about 200 years.
Similarly, when the Bible says that a king ruled for a certain number of years, it is unclear, even as the Talmud recognizes, whether the first and last years are full years of twelve months or parts of a calendar year (in the latter case, two kings would have ruled in the same year).
Additionally, most post-biblical events are based on questionable traditions. Tradition states that the second temple stood for 420 years, while scholars count the second temple period as over 580 years, from 516 BCE to 70 CE. The anno mundi calculation also assigns dates for people that are not even hinted at in Scripture; for instance, we have no idea how long King Saul reigned.
In short, there were and are people who do not accept the basic assumptions used by the anno mundi calculations. There were and are people who take the Bible literally but nevertheless develop different calculations of the time periods mentioned because they interpret the events differently. Nevertheless, as previously stated, many Jews are convinced that it is a religious duty to use this calendar and feel good when they date their correspondence with the anno mundi year.
 The most famous Christian version was not invented until 525 AD (After Death of Jesus—many use CE today, Common Era). It includes a calculation of the years since the birth of Jesus, believing he was born in the year 1. The author of this calendar made mistakes. A careful reading of the New Testament shows that Jesus was born sometime between 6 and 4 BC (Before Christ—many use BCE today, Before the Common Era).
 When Rosh Hashanah, the Jewish New Year, starts in September 2017, the Jewish anno mundi year will be 5778 since creation. This widely-used calendar dates the patriarch Abraham’s birth as 1948, the same year that the State of Israel was reestablished according to the currently-used secular calendar. It dates the giving of the Ten Commandments as 2448, which would be 3330 years before September 2017.
 The same time the Christian calendar was invented.
 It is possible that after the flood, the calculation of years changed and people considered the difference from a warm to a cold season as a year, so that two biblical years during this period equal to one year today. While the Bible states that Abraham lived 175 years, Isaac 180, Joseph 110, and Moses 120, they would have died at ages 87, 90, 55 and 60, respectively.
 This midrash is not based on anything in the Bible text and is contrary to what is stated.
 I Kings 6:1 seems to say the period lasted 360 years from the entry of the Israelites into Canaan until the onset of King Saul’s reign.