When the children of Israel were in Egypt Moses told Pharoah that they must go a three day journey into the wilderness to keep a feast to Yahweh (Exodus 8:23; 10:9).  Of course, Moses did not tell Pharoah that he meant the wilderness of Sinai, which itself was many days march from Egypt.  They reached the wilderness of Sinai on Sivan 1 (Exodus 19:1), and then they journeyed 3 days (Exodus 8:23), which brings us to Sivan 3.  Then they are told to wash and prepare themselves for two days and to be ready for the third day (Exodus 19:10-11).  Two days of preparation would be Sivan 4 and Sivan 5.  The third day is Sivan 6.     Now counting from the morrow of the Passover holy day, i.e. the 16th of Aviv, we have 14 days left in Aviv; 30 days in Ziv (the second month); and 6 days in Sivan: (14 + 30 + 6 =50).  The total is 50 days.     Back.