Two numbers in Japanese have two pronunciation alternatives.
- 四 / 4 can be pronounced either "よん" (yon) or "し" (shi)
- 七 / 7 can be pronounced either "しち" (shichi) or "なな" (nana)
I know that "し" (shi) can be avoided because it has the same pronunciation as "死" which means "death" but how strong is the taboo and how does it relate to factors such as formality and politeness when choosing which form to use? Is it just a matter of superstition or should speakers be more sensitive?
"しち" (shichi) vs "なな" (nana) seems to be less discussed since it doesn't involve taboo or superstition as far as I know but again what about formality and politeness etc?