'Fifteen' in the Bible

Now Bethany was nigh unto Jerusalem, about fifteen furlongs off:

Then sent Joseph, and called his father Jacob to him, and all his kindred, threescore and fifteen souls.

And sounded, and found it twenty fathoms: and when they had gone a little further, they sounded again, and found it fifteen fathoms.

Then after three years I went up to Jerusalem to see Peter, and abode with him fifteen days.