Hi Jdw11, Welcome to Wikipedia! I reverted your recent edit to Matrix norm because it was unnecessary: it was already stated just above that is a norm (multiplying by a constant like N does not change whether or not something is a norm). The comment at the end that it is not submultiplicative isn't meant to contradict that, since submultiplicativity isn't a norm requirement. It was just an extra piece of information. Also, your <ref> tag didn't work; in future try using the preview feature to check whether your edit looks the way you want it.