Most of the numbers get 'th' at the end to change to an ordinal number, except for the first three numbers:

Please note that apart from 1st, 2nd, and 3rd, the spelling of some of the numbers changes when 'th' is added to them.

As you can see in the table above, some of the numbers change form when 'th' is added to them.

For compound ordinal numbers, use this structure:
first part (in cardinal form) + hyphen + second part (ordinal form)

For the tens, note that the letter 'y' at the end of the cardinal numbers, turns into 'ie' in ordinal numbers.

To write a number from 100 to 999 in ordinal form, start by writing the number of hundreds. If there is nothing left over, add the suffix '-hundredth' to the end of the number. For example, '500' becomes 'five hundredth'.
If there are additional numbers beyond the hundreds, write the word 'hundred' followed by the rest of the numbers in ordinal form.

Roman numeral system numbers originated in ancient Rome where they used the letters I, V, X, L, C, D, and M to write numbers. Each of these letters represents a number: I for 1, V for 5, X for 10, L for 50, C for 100, D for 500, and M for 1000.
We can put the symbols in descending order from left to right and add numbers together. If we add all of the numbers' values together, we get the total value. For example:

We can also put a symbol with a smaller value on the left side of the one with a larger value and subtract the value of the smaller symbol from that of the larger symbol to get the total value. For example:

Ordinal numbers are used to indicate the position or order of things or objects in a sequence. Their purpose is to arrange different items in a specific order based on their position or standing. When objects or things are placed in a particular order, the counting procedure requires labeling them with numbers, and ordinal numbers help to tell their precise position or place them in order within a group.
Ordinal numbers are used in many different contexts, from everyday life to sports games, mathematics, and science. They are essential for organizing data, such as ranking sports teams, listing items in a menu or catalog, or describing events in a story or timeline. Let's see some examples:

The difference between cardinal and ordinal numbers is that we use cardinal numbers to count or indicate the quantity of things, therefore, any natural number is considered cardinal. For example:

But ordinal numbers are used to express the position or order of objects. For instance:

Ordinal and cardinal numbers regularly appear together, even to quantify the same object. When a cardinal number and an ordinal number modify the same noun, the ordinal number always comes first, before the cardinal number:

We also should know that two ordinal numbers cannot appear back to back. We cannot say 'the first second race', unless there is a word or punctuation between the two ordinal numbers.