基数词序数词缩写1one first1st 2two second2nd 3three third3rd 4four fourth4th 5five fifth5th 6six sixth6th 7seven seventh7th 8eight eighth8th 9nine ninth9th 10ten tenth10th 11eleven eleventh11th 12 twelve twevlfth12th 13thirteen thirteenth13th 14fourteen fourteenth14th 15fifteen fifteenth15th 16sixteen sixteenth16th 17seventeen seventeenth17th 18eighteen eighteenth18th 19nineteen nineteenth19th 20 twenty twentieth20th 21twenty-one twenty- first21st 22twenty-two twenty-second22nd 23twenty-three twenty-third23rd 24twenty-four twenty-fourth24th 25twenty-five twenty-fifth25th 26twenty-six twenty-sixth26th 27twenty-seven twenty-seventh27th 28twenty-eight twenty-eighth28th 29twenty-nine twenty-ninth29th 30thirty thirtieth30th 31thirty-one thirty-first31st 基变序，有规律；词尾加上th
一二三，特殊记；八去t来九去e
遇到ve变f； 以y结尾变ie
要是遇到几十几，只变个位就可以