Multidb Question

Hi there, got a question regarding multi-db. When i configure the move-blogs.php, what do i put to $newdb_prefix, this: $newdb_prefix = 'wm001'; or this $newdb_prefix = 'wm001_';

if i have 16 dbs, like wm001_0, wm001_1, wm001_2 etc. Should i put "_" after the dbprefix or not?