kanjiman8 wrote:

As far as I’m aware, the readings for 七 and 四 are interchangeable if purely saying the numbers on their own. なな is easier to distinguish than saying しち, as しち sounds similar to 一 (いち). As for 四, よん is preferred as し sounds similar to the reading for the word ‘death’ in Chinese 死 (sǐ). When you say the numbers 40 and 70, it’s 四十 (よんじゅう) and 七十 (ななじゅう) respectively.

When it comes to counting things, し and しち are both used with certain counters. For example:<br>
四月 (しがつ) = April<br>
七月 (しちがつ) = July<br>
七人 (しちにん) = Seven people<br>
七時 (しちじ) = 7 o’clock

If you’re interested, you can read more about unlucky numbers in Asian cultures here http://www.todayifoundout.com/index.php/2011/01/why-the-number-four-is-considered-unlucky-in-some-east-asian-cultures/.

Thank you very much for the explanation! So the reason why it is read like that is so as not to confuse it with another number?