Why “i” is used in for loops

Which in turn is certainly derived from index variables in math (i for summation/product; i,j for matrix indexing and so on).

Old FORTRAN programmer here... I hated implicit data types and was never happier when IMPLICIT NONE was introduced.

c.f. &quot;God is real (unless declared integer)&quot; <a href="https:&#x2F;&#x2F;ell.stackexchange.com&#x2F;questions&#x2F;163171&#x2F;god-is-real-unless-declared-integer" rel="nofollow">https:&#x2F;&#x2F;ell.stackexchange.com&#x2F;questions&#x2F;163171&#x2F;god-is-real-u...</a>