Words

Gus Polly

0	zero	10	twelve	20	twentel
1	one	11	twelve-one	30	thirtel
2	two	12	twelve-two	40	fortel
3	three	13	twelve-three	50	fiftel
4	four	14	twelve-four	60	sixtel
5	five	15	twelve-five	70	seventel
6	six	16	twelve-six	80	eighttel
7	seven	17	twelve-seven	90	ninetel
8	eight	18	twelve-eight	T0	tentel
9	nine	19	twelve-nine	E0	eleventel
T	ten	1T	twelve-ten	100	one gross
E	eleven	1E	twelve-eleven	200	two gross
1 000	one great	2 000	two great	10 000	twelve great
100 000	one gross great	1 000 000	one second great	1 000 000 000	one third great

10^(3n) one (n)th great
Other than replacing the -ty (from ten) with the -tel (from twELve) suffix, this system uses the words that are already there. Also, when approaching large numbers, we no longer have to worry about what prefix goes before the -illion, we just need to know how many sets of three digits there are, and know that it's that many greats.

Ordinal forms

1	first	2	second	3	third	4	fourth
5	fifth	6	sixth	7	seventh	8	eighth
9	ninth	T	tenth	E	eleventh	10	twelfth
10	twelfth	20	twentelth	30	thirtelth	40	fortelth
50	fiftelth	60	sixtelth	70	seventelth	80	eightelth
90	ninetelth	T0	tentelth	E0	eleventelth	100	grossth

For convenience here, T stands for ten and E for eleven).