Bass at "thang" in choruses is just extending the previous chord
The major 6/9 chord is a tone cluster centered around the root note;
some possibilities of how to play it are given.
ORDER: I C1 V1 PC1 C2 V2 PC2 C3 B FPC FC1 FC2 O
[INTRO]
(free tempo)
F#m | Dmaj7+11 | Dmaj7sus2 Aadd9/C# | Bmadd4 C#7-9 | (hold)
^ x467x7/x4643x
[CHORUS 1]
x20224 x43434
Bm13 C#7-9 F#m9
Age ain't nothing but a number, throwing down ain't nothing but a thang,
464554 x43435 x32232/8-x-9-9-10-10
G#7-13 C#7-13 F#m9 | F#m9 C6/9
This something I have for you it'll never change
x434x5
Bm9 C#7-13 F#m9
Age ain't nothing but a number, throwing down ain't nothing but a thang,
G#7-13 C#7-13 F#m9 | F#m9 C6/9
This something I have for you it'll never change
[VERSE 1]
Bm9 C#7-9 F#m9
Here I am, and there you are,
G#7-13 C#aug F#m9 C6/9
your eyes are calling me to your heart.
Bm9 C#7+9 F#m9
All you gotta do is knock, I'll let you in,
G#7-13 C#aug F#m9 C6/9
And we will feel the passion that flows within.
[PRE-CHORUS 1]
Bm13 C#7-9 F#m9
I don't mean to be bold, but I gotta let you know,
G#7-13 C#7-13 F#m9 C6/9
I gotta thang for you and I can't let go... ooh my
[CHORUS 2]
Bm9 C#7+9 F#m9
Age ain't nothing but a number, throwing down ain't nothing but a thang,
G#7-13 C#7-13 F#m9 | F#m9 C6/9
This something I have for you it'll never change
Bm9 C#7-9 F#m9
Age ain't nothing but a number, throwing down ain't nothing but a thang,
G#7-13 C#7-13 F#m9 | F#m9 C6/9
This something I have for you it'll never change
[VERSE 2]
Bm9 C#7+9 F#m9
Take my hand, and come with me,
G#7-13 C#aug F#m9 C6/9
let me show you to ectasy,
Bm9 C#7-9 F#m7
Boy be brave, don't be afraid,
G#7-13 C#aug F#m9 C6/9
cause tonight we're gonna go all the way.
[PRE-CHORUS 2]
Bm9 C#7+9 F#m9
Don't mean to be bold, gotta let you know,
G#7-13 C#7-13 F#m9 C6/9
I gotta thang for you, and I can't let go, ooh my...
[CHORUS 3]
Bm9 C#7-9 F#m9
Age ain't nothing but a number, throwing down ain't nothing but a thang,
G#7-13 C#7-13 F#m9 | F#m9 C6/9
This something I have for you it'll never change
Bm9 C#7+9 F#m9
Age ain't nothing but a number, throwing down ain't nothing but a thang,
G#7-13 C#7-13 F#m9 | F#m9 C6/9
This something I have for you it'll never change
[BRIDGE]
(bass not playing, different chord substitutions instead)
x20222 x53200
Bm9 Dm6/9 Amaj7
"So what's up, Here I am,
x20230
G#7+9 C#7-9/E# Amaj9/E Bm7add11
reach... baby
Bm9 Dm6/9 Amaj7
Come here...
G#7+9 Bm7-5 Amaj7 Bm7add11
Age ain't nothin' but a number ...ooh
[FINAL PRE-CHORUS]
(bass in, percussion light)
Bm9 C#7-9 F#m9
I don't mean to be bold, but I gotta let you know,
G#7-13 C#7-13 F#m9 C6/9
Liyah's got a thang for you and I can't let go...ooh my...
[FINAL CHORUS 1]
Bm9 C#7+9 F#m7
Age ain't nothing but a number, throwing down ain't nothing but a thang,
G#7-13 C#7-13 F#m9 | F#m9 C6/9
This something I have for you it'll never change
Bm9 C#7-9 F#m7
Age ain't nothing but a number, throwing down ain't nothing but a thang,
G#7-13 C#7-13 F#m9 | F#m9 C6/9
This something I have for you it'll never change
[FINAL CHORUS 2]
Bm9 C#7+9 F#m7
Age ain't nothing but a number, throwing down ain't nothing but a thang,
G#7-13 C#7-13 F#m9 | F#m9 C6/9
This something I have for you it'll never change
Bm9 C#7-9 F#m7
Age ain't nothing but a number, throwing down ain't nothing but a thang,
G#7-13 C#7-13 F#m9 | F#m9 C6/9
This something I have for you it'll never change
[OUTRO]
(repeat to fade)
Bm9 C#7-9 F#m7
Age ain't nothing but a number, throwing down ain't nothing but a thang,
G#7-13 C#7-13 F#m9 | F#m9 C6/9
This something I have for you it'll never change
Source: https://tabs.ultimate-guitar.com/tab/aaliyah/age_aint_nothing_but_a_number_chords_2062953