Masculine, animate nouns ending in a consonant: add а (acc = gen)

If the noun ends in a consonant or о, add а

Dative ending у: Masc noun ending in consonant - add у. If ends in о, replace with у.

m nouns ending in a consonant and neuter nouns ending in o, ending is -ом

Masculine nouns ending in a consonant add е

Nouns ending in я -- whether masc of fem -- replace with ю

Nouns ending in я -- whether masc or fem -- and fem nouns ending in ь, replace with и

Nouns ending in а or я -- regardless of gender -- replace with е (unless ends in ия - that becomes ии) [NOTE: Just like prepositional]

Nouns ending in я -- whether masc or fem -- replace with ей

Nouns ending in а, я, о, й (regardless of gender), and masculine nouns ending in ь, replace with е. (except -ия and -ий, replace with ии)

Masculine, animate nouns ending in й and ь, replace with я (acc = gen)

If the noun ends in й, е, and masc nouns ending in ь, replace with я

If noun ends in й, ь (masc), or е, replace with ю

m noun ending in ь or й, or neuter ending in е, ending is -ем (ём if stressed)

Nouns ending in ия, ий, or ие, replace with ии

NO CHANGE [acc = nom] for: (1) Inanimate masculine nouns, (2) Inanimate neuter nouns (most neuter nouns are inanimate), (3) fem nouns ending in ь.

The ten neuter nouns ending in -мя (время/time, имя/name, пламя/flame, семя/seed, стрёмя/stirrup, темя/crown of the head, вымя/udder, знамя/flag/banner, бремя/burden, племя/tribe), replace мя with мени

The ten neuter nouns ending in -мя (время/time, имя/name, пламя/flame, семя/seed, стрёмя/stirrup, темя/crown of the head, вымя/udder, знамя/flag/banner, бремя/burden, племя/tribe), replace мя with мени

The ten neuter nouns ending in -мя (время/time, имя/name, пламя/flame, семя/seed, стрёмя/stirrup, темя/crown of the head, вымя/udder, знамя/flag/banner, бремя/burden, племя/tribe), replace мя with менем

The ten neuter nouns ending in -мя (время/time, имя/name, пламя/flame, семя/seed, стрёмя/stirrup, темя/crown of the head, вымя/udder, знамя/flag/banner, бремя/burden, племя/tribe), replace мя with мени

Neuter nouns ending in е remain unchanged (unless ends in ие, then replace with ии)

Nouns ending in a -- whether masc or fem -- replace with у

Nouns ending in а -- whether masc or fem -- replace а with ы

Spelling Rule #1: Never write hard vowel ы after г, к, х, ж, ч, ш, щ; instead use и (even though after ж and ш, и is pronounced as if it were written ы).

Nouns ending in а -- whether masc or fem -- replace with ой

Nouns ending in а -- whether masc or fem -- replace with ой

Spelling Rule #3: No unstressed о after ж, ч, ш, щ, and ц instead use е.

Nouns ending in а -- whether masc or fem -- replace а with ы

F nouns ending in ь, ADD ю

Fem nouns ending in ь, replace with и

If noun ends in ия, replace with ии [Note: just like prepositional]

Some short m nouns, particularly monosyllabic ones, take -у (or -ю) when used with в or на ONLY. These nouns often denote places or locations. Examples:

• лёд (ice) - на льду
• год (year) - в году
• лес (forest) - в лесу
• берег (shore, river bank) - на берегу
• пол (floor) - на полу
• сад (garden) - в саду
• снег (snow) - в/на снегу
• угол (corner) - в/на углу
• шкаф (wardrobe) - в шкафу
• аэропорт (airport) - в аэропорту

These nouns take the normal -е ending after о