The British linguist David Crystal has written that the apostrophe ‘avoids an awkward juxtaposition of symbols, especially with plurals’. ns is one such case. Write it as n’s and if anyone tells you that the apostrophe means that something must belong to n, tell them not to be so stupid.

The British linguist David Crystal has written that the apostrophe ‘avoids an awkward juxtaposition of symbols, especially with plurals’. ns is one such case. Write it as n’s.