G11

G1B3D5F♭7A9C11

Six notes in theory; in practice the third is usually dropped, because the eleventh sits a half step above it.

What is true of it

G11 is G, B, D, F, A and C — 1, 3, 5, b7, 9 and 11 counted from G.

On an instrument that cannot reach all 6, the 3, 5 and 1 go first, in that order.