The album Winter Diary ~A7 Classical~

[pride123]

I'm guessing why they'd named it A7 Classical.
It's because the album consists of songs from A ONE and sixxxxxx.
And so.... A "ONE" + "sixxxxxx" : SEVEN.
So that's how they get A7!

[tsumekaze_]

Lol even though that should have been quite obvious I couldn't realize until you pointed it out XD I feel so stupid now. Well, now I know what it means

[Delirium-Zer0]

OMG I have been trying to figure it out XD Even if this isn't the case, honest to goodness I can't think of a better explanation than this one, lol!

[DonkeyKongRemix]

At least the people involved with the creation of this album knew how to do math.