Everyone starts with these one digit numbers:

number	cardinal number	ordinal number
0	zero	.
1	one	first
2	two	second
3	three	third
4	four	fourth
5	five	fifth
6	six	sixth
7	seven	seventh
8	eight	eighth
9	nine	ninth

Then, we learn the 'teens':

number	cardinal number	ordinal number
10	ten	tenth
11	eleven	eleventh
12	twelve	twelfth
13	thirteen	thirteenth
14	fourteen	fourteenth
15	fifteen	fifteenth
16	sixteen	sixteenth
17	seventeen	seventeenth
18	eighteen	eighteenth
19	nineteen	nineteenth

After that, the tens:

number	cardinal number	ordinal number
20	twenty	twentieth
30	thirty	thirtieth
40	forty	fortieth
50	fifty	fiftieth
60	sixty	sixtieth
70	seventy	seventieth
80	eighty	eightieth
90	ninety	ninetieth

And finally, the common Œbig numbersı :

number	cardinal number	ordinal number
100	hundred	hundredth
1,000	thousand	thousandth
10,000	ten thousand	ten thousandth
100,000	hundred thousand	hundred thousandth
1,000,000	million	millionth
10,000,000	ten million	ten millionth
100,000,000	hundred million	hundred millionth
1,000,000,000	billion	billionth

Scientists (and trivia buffs) might be interested in this list of 'really big numbers' :

number	cardinal number	a hint to help remember
10E12	trillion	tri as in triplets
10E15	quadrillion	quad as in quadruplets
10E18	quintillion	quint as in quintuplets
10E21	sextillion	sex as in sextuplets
10E24	septillion	sept as in September
10E27	octillion	oct as in October
10E30	nonillion	non as in November
10E33	decillion	dec as in December
10E100	googol	.
10E(10E100)	googolplex	.

What's next (all are short introductions to these topics, useful for English Language learners and young native speakers) :