Thread: Курю одну сигарету за другой; why другой?

I had thought that 'одну сигарету за другой' was all in accusative case; but with 'за', другой must be in feminine instrumental? Is that correct?

Одну сигарету за другой (сигаретой).

Сигаретой is just omitted as it's obvious what you're talking about anyway. As you can see сигаретой is in instrumental, just as you noted it should be.

As for другой, It's not a noun, it's an adjective. Adjectives declensions can be somewhat confusing. Particulary this one, because it's fememine instrumental form coincides with it's masculine nominative form.

'Одну сигарету за другой (сигаретой).'

That makes sense right there. It makes sense for другой to be an adjective.
Thanks!