9 charms make a 13" block (13 1/2" unfinished.) 6 blocks 6 blocks plus a 6" border will give you 90" square. How big do you want your quilt? I like mine bigger than that because my mattress is thick. Those 36 blocks would need 324 charms - you have 252. You can cut your own from fabric if you need more. Bonnie Hunter has bed sizes on her site, quiltsville.com Probably 6 X 5 plus the border would do full size quilt. 30 blocks would take 270 charms. If you choose a strong solid fabric and cut 5" squares for the center of the 9 patch, that'd give the 30 more so you'd have more than enough with your 6 packs.
I ran out of fabric with my D9P and had to cut some fabric and then use an on point setting to get it big enough for a lap quilt with only 2 charm packs.
Edit: Bellaboo, you and I were posting at the same time. At least my math is okay.
Last edited by irishrose; 10-28-2013 at 01:46 PM.