He's in first place.
Ordinal numbers indicate order, sequence or position.
| 1st | first | 20th | twentieth |
| 2nd | second | 21st | twenty-first |
| 3rd | third | 22nd | twenty-second |
| 4th | fourth | 23rd | twenty-third |
| 5th | fifth | 24th | twenty-fourth |
| 6th | sixth | 25th | twenty-fifth |
| 7th | seventh | 26th | twenty-sixth |
| 8th | eighth | 27th | twenty-seventh |
| 9th | ninth | 28th | twenty-eighth |
| 10th | tenth | 29th | twenty-ninth |
| 11th | eleventh | 30th | thirtieth |
| 12th | twelfth |
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| 13th | thirteenth | 40th | fortieth |
| 14th | fourteenth | 50th | fiftieth |
| 15th | fifteenth | 60th | sixtieth |
| 16th | sixteenth | 70th | seventieth |
| 17th | seventeenth | 80th | eightieth |
| 18th | eighteenth | 90th | ninetieth |
| 19th | nineteenth | 100th | (one) hundredth |
Note that we usually write smaller numbers in words (tenth) and bigger numbers in figures (40th), although there is no strict rule for this.
There are a lot of uses, for example, to talk about dates and anniversaries and to give directions.