1)
Here it says that there were 250 Sarei ha'Nitzavim on the Melachah, and in Melachim I, 9:23 it says 550! There (5:30) it says that there were 3,300 taskmasters, and above (2:17) it said 3,600!
1.
Refer to Melachim I, 5:30:2:1-4.
