基数词变序数词口诀基数词变序数词有规律口诀：(词尾加上th) 一、二、三特殊记，词字母t，d,d;八减t,九减e;f来把ve替；Ty变成tie.遇到几十几，只变各位就可以；1000 one thousand1000000 one million1000000000 one billion1000000000000 one trilliononce twice three times four times dozen fortnight score1 one2 two3 three4 four5 five6 six7 seven8 eight9 nine10 ten11 eleven12 twelve13 thirteen14 fourteen15 fifteen16 sixteen17 seventeen18 eighteen19 nineteen20 twenty 21 twenty-one22 twenty-two23 twenty-three24 twenty-four25 twenty-five26 twenty-six27 twenty-seven28 twenty-eight29 twenty-nine30 thirty31 thirty-one32 thirty-two33 thirty-three34 thirty-four35 thirty-five36 thirty-six37 thirty-seven38 thirty-eight39 thirty-nine40 forty41 forty-one42 forty-two43 forty-three44 forty-four45 forty-five46 forty-six47 forty-seven48 forty-eight49 forty-nine50 fifty51 fifty-one52 fifty-two53 fifty-three54 fifty-four55 fifty-five56 fifty-six57 fifty-seven58 fifty-eight59 fifty-nine60 sixty61 sixty-one62 sixty-two63 sixty-three64 sixty-four65 sixty-five66 sixty-six67 sixty-seven68 sixty-eight69 sixty-nine70 seventy71 seventy-one72 seventy-two73 seventy-three74 seventy-four75 seventy-five76 seventy-six77 seventy-seven78 seventy-eight79 seventy-nine80 eighty81 eighty-one82 eighty-two83 eighty-three84 eighty-four85 eighty-five86 eighty-six87 eighty-seven88 eighty-eight89 eighty-nine90 ninety91 ninety-one92 ninety-two93 ninety-three94 ninety-four95 ninety-five96 ninety-six97 ninety-seven98 ninety-eight99 ninety-nine 100 one hundred 第1 first第2 second第3 third第4 fourth第5 fifth第6 sixth第7 seventh第8 eighth第9 ninth第10 tenth第11 eleventh第12 twelfth第13 thirteenth 第14 fourteenth 第15 fifteenth 第16 sixteenth 第17 seventeenth 第18 eighteenth第19 nineteenth第20 twentieth第21 twenty-first第22 twenty-second第23 twenty-third第24 twenty-fourth第25 twenty-fifth第26 twenty-sixth第27 twenty-seventh第28 twenty-eighth第29 twenty-ninth第30 thirtieth第31 thirty-first第32 thirty-second第33 thirty-third第34 thirty-fourth第35 thirty-fifth第36 thirty-sixth第37 thirty-seventh第38 thirty-eighth第39 thirty-ninth第40 fortieth第41 forty-first第42 forty-second第43 forty-third第44 forty-fourth第45 forty-fifth第46 forty-sixth第47 forty-seventh 第48 forty-eighth第49 forty-ninth第50 fiftieth第51 fifty-first第52 fifty-second第53 fifty-third第54 fifty-fourth第55 fifty-fifth第56 fifty-sixth第57 fifty-seventh 第58 fifty-eighth第59 fifty-ninth第60 sixtieth第61 sixty-first第62 sixty-second第63 sixty-third第54 sixty-fourth第65 sixty-fifth第66 sixty-sixth第67 sixty-seventh 第68 sixty-eighth第69 sixty-ninth第70 seventieth第71 seventy-first第72 seventy-second第73 seventy-third第74 seventy-fourth第75 seventy-fifth第76 seventy-sixth第77seventy-seventh第78 seventy-eighth第79 seventy-ninth第80 eightieth第81 eighty-first第82 eighty-second第83 eighty-third第84 eighty-fourth第85 eighty-fifth第86 eighty-sixth 第87 eighty-seventh 第88 eighty-eighth 第89 eighty-ninth第90 ninetieth第91 ninety-first第92 ninety-second第93 ninety-third第94 ninety-fourth第95 ninety-fifth第96 ninety-sixth第97 ninety-seventh第98 ninety-eighth第99 ninety-ninth第100 one hundredth序数词下面把1－99的序数词分为四类:1、第一类first (1st) 第一second (2nd) 第二third (3rd) 第三（在括号里的是缩写形式，均在阿拉伯数字后面加上相应序数词的最后两个字母构成，以下各类与此相同。
基数词变序数词口诀：第一、二、三要全变，（即first ，second ，third 没有规律，需死记硬背）其它th 加后边，（基本规律是在词尾加th）加th 时有例外，你需格外记明白：八减t ，(eight-eighth)九去 e ，(nine-nith)字母f 代ve ，(five-fifth, twelve-twelfth)ty 变成tie ，(即以ty 结尾的整十数把ty 变成tie：twenty-twentieth,thirty-thirtieth....)然后再加th ，若是遇到两位数，十位基数个位序。
基数词：1 one 2 two 3 three 4 four 5 five 6 six 7 seven 8 eight 9 nine 10 ten 11 eleven 12 twelve 13 thirteen 14 fourteen 15 fifteen 16 sixteen 17 seventeen 18 eighteen 19 nineteen 20 twenty 21 twenty-one 22 twenty-two 23 twenty-three 24 twenty-four 25 twenty-five 26 twenty-six 27 twenty-seven 28 twenty-eight 29 twenty-nine 30 thirty 31 thirty-one 32 thirty-two 33 thirty-three 34 thirty-four 35 thirty-five 36 thirty-six 37thirty-seven 38 thirty-eight 39 thirty-nine 40 forty 41 forty-one 42 forty-two 43 forty-three 44 forty-four 45 forty-five 46 forty-six 47 forty-seven 48 forty-eight 49 forty-nine 50 fifty 51 fifty-one 52 fifty-two 53 fifty-three 54 fifty-four 55 fifty-five 56 fifty-six 57 fifty-seven 58 fifty-eight 59 fifty-nine 60 sixty 61 sixty-one 62 sixty-two 63 sixty-three 64 sixty-four 65 sixty-five 66 sixty-six 67 sixty-seven 68 sixty-eight 69 sixty-nine 70 seventy 71 seventy-one 72 seventy-two 73 seventy-three 74 seventy-four 75 seventy-five 76 seventy-six 77 seventy-seven 78seventy-eight 79 seventy-nine 80 eighty 81 eighty-one 82 eighty-two 83 eighty-three 84 eighty-four 85 eighty-five 86 eighty-six 87 eighty-seven 88 eighty-eight 89 eighty-nine 90 ninety 91 ninety-one 92 ninety-two 93 ninety-three 94ninety-four 95 ninety-five 96 ninety-six 97 ninety-seven 98 ninety-eight 99 ninety-nine 100 one hundred第1 first 1st第2 second 2nd第3 third 3rd第4 fourth 4th第5 fifth 5th第6 sixth 6th第7 seventh 7th第8 eighth 8th第9 ninth 9th第10 tenth 10th第11 eleventh 11th第12 twelfth 12th第13 thirteenth 13th第14 fourteenth 14th第15 fifteenth 15th第16 sixteenth 16th第17 seventeenth 17th第18 eighteenth 18th第19 nineteenth 19th第20 twentieth 20th第21 twenty-first 21st第22 twenty-second 22nd 第23 twenty-third 23rd第24 twenty-fourth 24th 第25 twenty-fifth 25th第26 twenty-sixth 26th第27 twenty-seventh 27th第28 twenty-eighth 28th 第29 twenty-ninth 29th 第30 thirtieth 30th第31 thirty-first 31st第32 thirty-second第33 thirty-third第34 thirty-fourth第35 thirty-fifth第36 thirty-sixth第37 thirty-seventh第38 thirty-eighth第39 thirty-ninth第40 fortieth第41 forty-first第42 forty-second第43 forty-third第44 forty-fourth第45 forty-fifth第46 forty-sixth第47 forty-seventh第48 forty-eighth第49 forty-ninth第50 fiftieth第51 fifty-first第52 fifty-second 第53 fifty-third第54 fifty-fourth第55 fifty-fifth第56 fifty-sixth第57 fifty-seventh 第58 fifty-eighth第59 fifty-ninth第60 sixtieth第61 sixty-first第62 sixty-second 第63 sixty-third第64 sixty-fourth 第65 sixty-fifth第66 sixty-sixth第67 sixty-seventh 第68 sixty-eighth 第69 sixty-ninth第70 seventieth第71 seventy-first第72 seventy-second 第73 seventy-third第74 seventy-fourth 第75 seventy-fifth第76 seventy-sixth第77 seventy-seventh 第78 seventy-eighth 第79 seventy-ninth第80 eightieth第81 eighty-first第82 eighty-second 第83 eighty-third第84 eighty-fourth第85 eighty-fifth第86 eighty-sixth第87 eighty-seventh 第88 eighty-eighth第89 eighty-ninth第90 ninetieth第91 ninety-first第92 ninety-second 第93 ninety-third第94 ninety-fourth第95 ninety-fifth第96 ninety-sixth第97 ninety-seventh 第98 ninety-eighth第99 ninety-ninth第100 one hundredth。
基数词变序数词口诀英语中基数词变为序数词时，一般在基数词后加词尾-th，但有几个词变化特殊，只要记住下面这个口诀，这些问题即可迎刃而解。
一、二、三，单独记；八去t，九除e，ve要用f替，整十基数变序数，先把ty变成tie；要是遇到两位数，十位基数个位序，th最后加上去。
解析口诀：one→first，two→second，three→third这三个词变化特殊，要单独记；eight→eighth，nine→ninth，八去t，九去e后再加-th；five→fifth，twelve→twelfth，五和十二把ve换成f再加-th；twenty→twentieth，thirty→thirtieth... 整十先把词尾y改为ie再加-th。
两位数时则十位数用基数词，个位数用序数词，如：twenty-first。
基变序有规律词尾加上th123 特殊记八去t 九去eve要用f替见y变成t和e要是遇到几十几只变个位就可以基变序有规律，一二三单独记，th结尾从四起，8去t ，9去e，5和12变ve（为f），整十前变y为ie（th）跟上去，几十几个变序数目再大同一个理数词的分类一. 基数词表示数目的词称为基数词。
其形式如下：1．1——10 one，two，three，four，five，six，seven，eight，nine，ten．2．11——19（十几都以-teen结尾）a) eleven，twelve，thirteen，fifteen，eighteenb) fourteen，sixteen，seventeen，nineteen(都是由其个位数形式后添加后缀-teen构成)3．21——99（整几十都以-ty结尾）a) twenty，thirty, forty，fifty，eightyb) sixty，seventy，ninety(都是其个位数形式后添加后缀-ty 构成)c) 表示几十几时，在几十和个位基数词形式之间添加连字符“-”21 twenty-one76 seventy-six4．百位数个数基数词形式加“hundred ['hʌndrəd]”，表示几百，在几十几与百位间加上and．101 a hundred and one320 three hundred and twenty648 six hundred and forty-eightE．千位数以上从数字的右端向左端数起，每三位数加一个逗号“，”。
