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APOSTROPHE

Plurals of abbreviations without periods and of figures are generally formed with s, no apostrophe.

For abbreviations with periods and letters of the alphabet used as nouns, add apostrophe plus s.

If double s combinations occur, add apostrophe plus s.

Plurals of italicized letters add italic apostrophe plus roman s.
 
VIPs
GIs
TVs

1890s
C-54s
type 2s
Ph.D.'s
ABC's
SOS's
straight A's
p's and q's
his Scottish r's
See also POSSESSIVES.