--- Morphology function to get plural form of the number
-- @param input number
-- @param table morphology plural forms
-- @param bool (default true) to include number or return just the word
function pluralForm(number, forms, includeNumber)
    if(#forms == 2) then
        forms[3] = forms[2]
    elseif(#forms ~= 3) then
        error("pluralForm: not enough elements in 'forms' argument")
    end
    local cases = {2,0,1,1,1,2}
    local result = ""
    if(includeNumber or includeNumber == nil) then
        result = result .. number .. ' '
    end
    return result .. forms[ ((number % 100 > 4 and number % 100 < 20) and 2 or cases[math.min(number % 10, 5)+1])+1 ]
end

print(pluralForm(1, {"юнит", "юнита", "юнитов"}))
print(pluralForm(3, {"юнит", "юнита", "юнитов"}))
print(pluralForm(5, {"юнит", "юнита", "юнитов"}))
print(pluralForm(1, {"unit", "units"}))
print(pluralForm(3, {"unit", "units"}))
print(pluralForm(5, {"unit", "units"}))
print(pluralForm(1, {"Получен новый предмет!", "Получены новые предметы!"}, false))
print(pluralForm(5, {"Получен новый предмет!", "Получены новые предметы!"}, false))

1 юнит
3 юнита
5 юнитов
1 unit
3 units
5 units
Получен новый предмет!
Получены новые предметы!

print(pluralForm(1, {L("юнит","unit"), L("юнита","units"), L("юнитов","units")}))