육, 륙 or 뉵 for number 6?

Question

I have a doubt concerning how to properly write the digit 6 in hangeul. As far as I understood, its pronunciation varies between 육 and 뉵, but it's never written 뉵.

I saw an extract from an older Korean textbook, where the alternatives for 6 are cited as 육 and 륙, but the only usage examples given were number 60 (육십) and 16 (십륙). As for 16, it was specified that the pronunciation is shim-nyuk rather than "ship-ryuk".

In a recent grammar guide, the spelling 륙 is never referred: it suggests that the spelling of 6 is always 육, being pronounced (but not spelled) as nyuk when it fills the ones bracket of a tens numeral (26, 36, 46, etc.).

A few questions:

1. Is 106 pronounced 백육?
2. Does the spelling 륙 still exist, as in 십륙, or is it spelled 십육, although pronounced [심뉵]?
3. Is the [뉵] pronunciation of 6 used only immediately after 십?

Answer 1

It will help to think of spelling and pronunciation separately.

• spelling

1. 6 in all single or multi-digit numbers are written as 육. So 16 is written as 십육 and pronounced as /심뉵/.
2. When the word is read as a string of single digit numerals, 6 is written 륙 only if it comes after a syllable ending with ㄹ or a vowel: A. in strings of digits as in phone numbers. 266-1600 (이륙육(의) 일륙공공).
   B. in informally or-ed numbers. 오륙 명 = five or six people (doesn't mean fifty six).
   C. when numbers form a proper name. 오륙도 (an island), 오일륙 (5/16/1961), 십이륙 (10/26/1979).
   (Note that 오일륙, etc. are treated like names referring to the event on that date.)

The reason for the two different spelling is because the original pronunciation is 륙 but Korean phonetics shun the ㄹ sound at the beginning of words or constituent sub-words of a compound word. So it changes to the variant 육 in most positions except when it attaches to another part like a suffix. The digits in multi-digit numbers are treated like head positions (since every digit is equally important), so numeric values only have 육.

• pronunciation

1. 육 is written and pronounced as /륙/ after a syllable ending with ㄹ (2-A above).
2. 육 is pronounced as /뉵/ after a syllable ending with ㄱ,ㄴ,ㄷ,ㅁ,ㅂ,ㅇ,ㅈ, etc (but only ㄱ,ㄴ,ㅁ,ㅂ,ㅇ actually exist in numerals). e.g. 106 (as a number) = 백육 = /뱅뉵/. 106 (as individual digits) = 일공육 = /일공뉵/.

The reason for the above has to do with general Korean phonology. For example, ㄱ followed by an 이-sound becomes /ㅇ-ㄴ/ sound if it happens across a morpheme or concept boundary. So 한국 요리 is pronounced /한궁뇨리/, while 확인 is just /화긴/ and not /황닌/ because 확 and 인 don't form independent concepts. There is a whole slew of these (rather complex) phenomena that apply to all 이-based vowels (이,야,얘,여,예,요,유) and not just 육.

• about your questions

1. Is 106 pronounced 백육?
   A: /뱅뉵/ if it's a single number, /일공뉵/ if it's a string of individual digits.
   (Note 백육 is pronounced either /뱅뉵/ or /배귝/ and no other way. "백육" doesn't represent pronunciation)

2. Does the spelling 륙 still exist, as in 십륙, or is it spelled 십육, although pronounced [심뉵]?
   A: 륙 doesn't exist in mathematical numbers like 16 (for this, 십육 is the only correct spelling), but it exists in numeral lists and names (오륙도, 십이륙).

3. Is the [뉵] pronunciation of 6 used only immediately after 십?
   A: No. There are other cases like 106 (/뱅뉵/), 1,600 (/천뉵빽/), 16,000 (/만뉵천/), etc.

Lastly I'd like to mention that all this is complicated stuff (kind of an anomaly in the language) most native speakers make mistakes about (and don't even care much). And people will understand you even if you don't write or say them exactly right, so don't stress yourself too much about it.