How many 5 inch quilt squares will you need to make a king size quilt measureing 120x124 with no border?

ACK !

120 divided by 4.5 ( allowing for quarter inch seams ) = 26 blocks wide.

124 divided by 4.5 ( allowing for quarter inch seams ) -= 27 blocks deep.

( These are rounded numbers, since 27 blocks wide, is actually 26.66666

and 27.5555 blocks. ) For a total of 702 blocks.

If you prefer, make 24 blocks wide and 26 blocks deep, and make up the difference in finished size with your border. 624 blocks.