“If a noun tells about one or more than one is called Number .
“ Number are as follows ” :-“ If a noun tells about only one . It is called Singular Number .
Ex. Student, Teacher etc.
“ If a noun tells about more than one . It is called Plural Number.
Ex. Pens, Boys, Teachers etc.
Rule No. 1 :-
Ex. chair → chairs, play → plays
Rule No. 2 :-
Ex. Brush → Brushes, Box → Boxes, Dash → Dashes, Class → Classes, Fix → Fixes, Quiz → Quizes etc.
Rule No. 3 :-
Ex. Mosquito → Mosquitoes, Tomato → Tomatoes, Mango → Mangoes etc.
Rule No. 4 :-
Ex. photo → photos, piano → pianos, bamboo → bamboos, radio → radios etc.
Rule No. 5 :-
Ex. Lady → Ladies, Duty → Duties, Nursery → Nurseries etc.
Rule No. 6 :-<
Ex. Key → Keys, Pay → Pays, Journey → Journeys etc.
Rule No. 7 :-
Ex. Life → Lives, Knife → Knives, Shelf → Shelves etc.
Rule No. 8 :-
Ex. Proof → Proofs, Belief → Beliefs, Gulf → Gulfs, Safe → Safes etc.
Rule No. 9 :-
Ex. Man(sing.) → Men(plu.), Child(sing.) → Children(plu.) etc.
Rule No. 10 :-
Ex. Bacterium → Bacteria, Medium → Media/Mediums, Minimum → Minima, Ovum → Ova, Pendulum → Pendulums etc.
Exceptions :- Forum → Forums/Fora, Dictum → Dicta, Auitorium → Auditoriums, Formula → Formulas/Formulae etc.
Rule No. 11 :-
Ex. Axis → Axes, Basis → Bases, Oasis → Oases, Synopsis → Summary, Metamorphosis → Metamorphoses, Narcosis → Narcoses etc.
Rule No. 12 :-
Ex. Fungus → Fungi, Radius → Radii, Cactus → Cacti, Nucleous → Nuclei etc.
Exception :- Syllabus → Sullabi/Syllabus, Propectus → Propecti/Propectus, Bonus → Bonuses, Virus → Viruses, Genius → Genuises.
Rule No. 13 :-
Ex.
Wit(ability to talk)(sing.) → Wits(intelligences)(plu.)
Advice(sing.) → Advices(plu.)
Iron(sing.) → Irons(plu.)
Good(sing.) → Goods(plu.)
Vesper(sing.) → Vespers etc.
Rule No. 14 :-
Ex.Phenomenon → Phenomaena, Criterion → Criteria etc.
Rule No. 15 :-
Common Noun + ful → n(c/s) + s → N(e/plu)
Ex.Glass + ful → Glassfuls
Mouth + ful → Mouthfuls
Rule No. 16 :-
Son-In-Law → Sons-In-Law
Brother-In-Law → Brothers-In-Law
Chief Minister → Chief Ministers etc.