most numbers ending with "1" (in any gender: , , ) require nominative singular for a noun: (21 cars), (151 people). most numbers ending with "2", "3", "4" (, , ) require genitive singular: (3 dogs), (42 windows). all other numbers (including 0 and those ending with it) require genitive plural: (5 apples), (10 rubles). genitive plural is also used for numbers ending with 11 to 14 and with inexact numerals: (111 meters); (many houses). nominative plural is used only without numerals: (these houses); cf. (3 houses; g. sg.). these rules apply only for integer numbers. for rational numbers see below.