How does the Russian 1-2-5 rule work?

Russian picks the noun form from the last two digits of the count. Numbers ending in 1 (but not 11) take the nominative singular, numbers ending in 2 to 4 (but not 12 to 14) take the genitive singular, and everything else takes the genitive plural.

Why is 11 different from 1?

Numbers from 11 to 14 are exceptions that always take the genitive plural (many) form, even though their last single digit might suggest one or few. The rule checks the last two digits precisely so одиннадцать рублей is correct, not одиннадцать рубль.

What are the three forms I need to enter?

ONE is the nominative singular (рубль), FEW is the genitive singular used after 2 to 4 (рубля), and MANY is the genitive plural used after 0, 5 to 20 and most other counts (рублей). Many nouns supply these in any dictionary.

Does this work for any Russian noun?

Yes. The 1-2-5 selection logic is identical for every noun; only the three word forms change. Supply the correct forms for your noun, or start from a preset, and the tool agrees the number for you.

Does it handle 0 and large numbers?

Yes. Zero takes the genitive plural (ноль рублей), and large numbers are judged purely on their last two digits, so 1001, 22 and 25 all resolve correctly.

Russian Plural Helper

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Russian noun agreement after a number is famously tricky: the same noun changes shape depending on the count. This helper applies the standard 1-2-5 rule so you always get один рубль, два рубля, пять рублей right — for any noun and any number.

How it works

Russian selects one of three forms from the last two digits of the count:

ends in 1, but not 11        -> ONE   (nominative singular)   1 рубль, 21 рубль
ends in 2-4, but not 12-14   -> FEW   (genitive singular)     2 рубля, 23 рубля
everything else              -> MANY  (genitive plural)       5 рублей, 11 рублей, 0 рублей

In code the test is n % 10 == 1 && n % 100 != 11 for ONE, n % 10 in 2 to 4 and n % 100 outside 12 to 14 for FEW, and MANY otherwise. The teens 11 to 14 are the trap — they always take MANY despite their final digit.

Example

For рубль (forms рубль / рубля / рублей):

1 рубль, 2 рубля, 5 рублей
21 рубль, 22 рубля, 25 рублей
11 рублей, 12 рублей, 14 рублей (teens always MANY)
101 рубль, 102 рубля (last two digits 01 and 02)

Tips

Always supply the genitive singular and genitive plural correctly — they are often different stems (год / года / лет). Some nouns have an irregular MANY form (человек after numbers becomes человек, not людей). The preset list covers the most common everyday nouns; for anything else, copy the three forms from a dictionary and the tool handles the agreement automatically.