In English, when the cardinal number is changed to ordinal number, the suffix -th is usually added after the cardinal number, but a few words have special changes. All these problems can be solved by remembering the following formula.

One, two, three, respectively; Eight pairs of t, nine pairs of e, ve should be replaced by f, all ten cardinal numbers should be replaced by ordinal numbers, and ty should be replaced by tie first; If you encounter two digits, the radix of the ten digits is the bit order, and then add th.

Analysis formula: Special changes in 1 → 1, 2 → 2, 3 → 3 should be recorded separately; Eight → eight, nine → nine, eight to t, nine to e and then-th; Five → fifth, else → twelfth, fifth, twelfth, replace ve with f and add-th; Twenty → twenty, thirty → thirty ... change the suffix y to ie, and then add -th. When there are two digits, the base number is used for the ten digits and the ordinal number is used for the single digits, such as twenty-one.

First ( 1st) first

Second second

the third time

(Abbreviations in brackets are composed of Arabic numerals followed by the last two letters of ordinal numbers, and the following categories are the same. There are only three such ordinal numbers, which is quite special in the whole ordinal number. Just like the first cardinal word, you need to recite it one by one.

2, the second category:

the fourth time

Fifth session

Sixth session

Seventh session

The eighth (eighth)

Ninth session

Tenth (10)

Eleventh session (1 1 session)

Twelfth (12) Twelfth

Thirteenth session (13)

14th session (14th session)

Fifteenth (15) Fifteenth

16th (16th) 16th

Seventeenth (17) Seventeenth

18th session (18th session)

Nineteenth (19) Nineteenth

There are sixteen ordinal numbers in this category. They are all formed by adding the suffix -th after the corresponding cardinal words. Pay attention to the spelling of the fifth, eighth, ninth and twelfth words.

3, the third category:

Twentieth (twentieth)

Thirtieth

Fortieth session

Fiftieth session

Sixtieth session

1/2

The seventieth session

The eightieth session

Ninetieth session

This category is all ordinal numbers of ten integers, with eight * * *. They are formed by changing Y in the suffix -ty of the corresponding ten-digit integer to I and adding the suffix-eth.