We see with the account of Noah, how the months all were 30 days long, giving a 360 day year. Notice when the flood began
In the six hundredth year of Noah’s life, on the seventeenth day of the second month—on that day all the springs of the great deep burst forth, and the floodgates of the heavens were opened. (Genesis 7:11)
… Flood starts day 17 of 2nd month … then
The waters flooded the earth for a hundred and fifty days. (Genesis 7:24)
followed by …
The water receded steadily from the earth. At the end of the hundred and fifty days the water had gone down, 4 and on the seventeenth day of the seventh month the ark came to rest on the mountains of Ararat. (Genesis 8: 3-4)
150 days brings us to month 7, day 17, exactly 5 months after the start. So every month was 30 days long. Thus the calendar used in Torah was different than the traditional Hebrew lunar calendar (where months are 28 or 29 days long) and also different from the modern calendar (with months 30, 31 or 28 days). The calendar used was 12 month, 30days/month, giving a 360-day year. Ezekiel and Daniel follow this lead.