What is this lead-sheet chord?

Question

So, I have recently been studying for a theory test (blecch!), and as part of that I have been learning lead sheet notation.

In one of the review questions I have come across this chord which I can't make sense of. Here is a transcript of the question instructions, along with the question itself:

Fill in the letter name of the bass note for each given chord in the specified key.
Name the bass note in the example on the right using lead sheet notation. 
Use harmonic minor.

Key of: | Chord: | Bass Note:
 A Maj  |   ii6  |   ????

Is this a real chord, or is it just a typographical error?

Answer 1

It's definitely a real chord!

The Roman numerals indicate the root of the chord, and the Arabic numerals next to it tell us the inversion; we call these latter numbers "figured bass."

A "6" in the figured bass indicates a first-inversion chord, and thus the chordal third will be in the bass. A "64" indicates a second-inversion chord, with the chordal fifth in the bass.

Thus this ii6 is a chord built on scale-degree 2 of A major, which is B. Also note that the case of the Roman numeral tells us the quality. Lowercase implies a minor chord, uppercase implies a major chord. Thus this B chord will be minor. The "6" in the figures tells us the chordal third is in the bass, meaning D will be the lowest note (because the entire chord is B–D–F♯).

I'd also invite you to check out some of your other answers: you have the root correct for your first two chords, but it looks like you've forgotten to consider the inversion. Also doublecheck the inversion for the V6 chord in B minor, although you're quite close. (And a final friendly hint: remember to use the leading tone in minor, especially with V chords!)

Answer 2

The important thing is to distinguish chord roots from bass tones. Roots are the tone upon which chords are built by stacking thirds. The bass is any chord tone placed into an octave to make it the lowest tone. When the root is not the bass, the chord is called inverted.

A visual in notation should help...

...Chord roots in blue, chord thirds in green, and chord fifth in red. Where applicable a scale leads from tonic up to the root of the given chord in root position (I did that to show how we count up the scale with Roman numerals to get chord roots) then the inverted chord is given. The bass notes of the final inverted chords are: B, D, A#, and D.

The Arabic numerals of Roman numeral analysis are kind of cryptic as they derive from the old practice of figured bass, but the basics are or 6/3 - often abbreviated to just 6 - means first inversion where the chord's third is in the bass, and 6/4 means second inversion with the chord's fifth in the bass. Root position chords are usually without the Arabic numerals or have 5/3.

Answer 3

This is no typo!

I = tonic = a,c#,e

II = second degree of A is b-minor = b,d,f#.

(ii6 = 1st inversion => d,f#,b). Bass note = D.

The Arabic numbers designate the inversions: 46 = forth-sixth, 6 = 3rd-6th.

In figured bass the Roman number designates the degree: as A = I then II = B)

Arabic numbers designate the inversion.

I = root position (135) => No numbers, because 3rd and 5th are not assigned.

So the inversions of the triads are:

C#,e,a => the I6 chord (first inversion) this means a,c#,e is inverted to c#,e,a, we have a third and a sixth above c#, and the bass tone c# is the third of the root chord ac#e.

The second inversion of this triad will be e,a,c#. The bass note is the fifth and we have a fourt and a sixth above the bass note: I46

(Next step will be the tetrads = seventh chords and their inversions.)