What is the next common multipul of 9 and 21?

The next common multiple of 9 and 21 can be found by determining their least common multiple (LCM). The LCM of 9 and 21 is 63, as it is the smallest number that both 9 and 21 divide evenly into. Therefore, the next common multiple of 9 and 21, after 0, is 63.