Hot answers tagged calendar
Technically you could date a check in Israel with the year 5774, and it would be valid; however, few people do so. The "Hebrew date", including the year, is used on Jewish marriage and divorce documents -- though they specify "according to the year 5774 to the world's creation, according to the counting used in this location of X", to make clear that we're ...
The red-letter days listed in your question are, indeed, the only times we say it, and for the reason you quote: because those are the days the musaf sacrificial offerings were offered to God in the Temple back in the good old days. See Numbers chapters 28–29.
The year "0" is not arbitrary. It is based on the date of creation assuming that the Torah description of creation is basically literal. That is, whether it is from the physical creation, or (as some believe) from the development of sapience in the first human being (Adam), or from the development of the first person to a level that allowed prophesy (Adam), ...
Why do we not say Hallel on Purim? It says in Megilla 14a that one of the reasons why Purim you do not say hallel is. "The miracle had no connection to the land of Israel, unlike the other holidays." (Look at the Gemorah or the link for more reasons why you do not say hallel on Purim which can connect to this question.)
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