Charles Ellicott Commentary 1 Chronicles 25:7

"And the number of them, with their brethren that were instructed in singing unto Jehovah, even all that were skilful, was two hundred fourscore and eight." — 1 Chronicles 25:7 (ASV)

So the number of them, with their brethren ... was two hundred fourscore and eight. —This total of two hundred and eighty-eight skilled musicians (24 × 12) shows that each of the twenty-four leading minstrels, called in 1 Chronicles 25:2–4 the “sons” of Asaph, Jeduthun, and Heman, was associated with a company of eleven “brethren,” who were experts in the chanting of the sanctuary. The twenty-four leaders accompanied the singing of their choirs with instrumental music.