Pluralize a single letter

To form the plural of a single letter, italicize the letter and add an apostrophe followed by the unitalicized letter s.

Recommended: We called tech support because the printer wasn't printing uppercase B's or lowercase p's.

Recommended: The fancy tittle on the i's is distracting.

When the capitalization is irrelevant, use uppercase.

Recommended: Mind your P's and Q's.