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1.04 Plurals

Add an s, but not an apostrophe, to form the plural of most abbreviations:

  • ADMs
  • BMWs
  • CAs
  • CRs
  • FTEs
  • GICs
  • MPs
  • PCBs
  • 747s

Use an apostrophe and s to form the plural of numerical names of aircraft ending in a single letter:

  • 727-100C’s
  • 747B’s
  • Cessna 402B’s

In cases where the resulting form would be ambiguous, add an apostrophe before the s:

  • c.o.d.’s
  • Q’s and A’s
  • SIN’s

Add an apostrophe and s to form the plural of abbreviations containing more than one period, and an s without an apostrophe, to form the plural of abbreviations with only one period. In the latter case, the s precedes the period:

  • G.M.’s
  • Gens.
  • pts.

The plurals of Mr. and Mrs. are irregular:

  • Mr.
    • Messrs.
  • Mrs.
    • Mmes.

The plural forms of the abbreviations for certain bibliographic references are different:

  • l. (line)
    • ll. (lines)
  • p. (page)
    • pp. (pages)
  • f. (and the one following)
    • ff. (and those following)
  • c., ch. (chapter)
    • c., ch. (chapters)
  • MS (manuscript)
    • MSS (manuscripts)
  • s. (section)
    • ss. (sections)
  • subs. (subsection)
    • subss. (subsections)

Note that SI/metric symbols maintain the same form for both singular and plural and are written without periods, except at the end of a sentence:

  • 1 cm
  • 5 cm, centimetres
  • 75 kg, kilograms
  • The boxer weighed only 75 kg, kilograms.