1 Chronicles 21:5

And Joab gave the sum of the number of the people unto David. And all they of Israel were a thousand thousand and an hundred thousand men that drew sword; and Judah was four hundred threescore and ten thousand men that drew sword. The apparent discrepancy between this passage and 2 Samuel 24:9 is due to the fact that this later account includes all those who would be available in war, while the other evidently speaks only of such as had had training in war.