1、基数词：表示数目多少。
1 one 11 eleven 21 twenty-one
2 two 12 twelve 22 twenty-two
3 three 13 thirteen 30 thirty
4 four 14 fourteen 40 forty
5 five 15 fifteen 50 fifty
6 six 16 sixteen 60 sixty
7 seven 17 seventeen 70 seventy
8 eight 18 eighteen 80 eighty
9 nine 19 nineteen 90 ninety
10 ten 20 twenty 100 hundred
注意：数字“0”可以读作“zero”，也可以读作字母“o”。
2、序数词：表示顺序先后。
1st first 11th eleventh 21st twenty-first
2nd second 12th twelfth 22nd twenty-second
3rd third 13th thirteenth 30th thirtieth
4th fourth 14th fourteenth 40th fortieth
5th fifth 15th fifteenth 50th fiftieth
6th sixth 16th sixteenth 60th sixtieth
7th seventh 17th seventeenth 70th seventieth
8th eighth 18th eighteenth 80th eightieth
9th ninth 19th nineteenth 90th ninetieth
10th tenth 20th twentieth 100th hundredth
基数词变序数词记忆口诀：
一、二、三，需要记，八去t，九省e，ve结尾时，f来代替，
ty结尾时，y变ie，再加th，若是几十几，前基后序别忘记。
