Ny Instances: Use apostrophes for plurals of abbreviations that have capital letters and intervals: M.D.’s, C.P.A.’s. Also use apostrophes for plurals formed from one letters: He acquired A’s and B’s on his report card. Mind your p’s and q’s. There would not appear to be any consensus on this at https://wavesocialmedia.com/story5615755/5-simple-statements-about-used-cars-uk-explained