# Ordinal Numbers

Counting numbers serves as a foundation for learning more about the position of a number in an orderly arrangement of the set of numbers. How do you represent a number’s precise location in a given list of numbers? For example, ‘Crayons are kept in the third box on the shelf,’ or ‘Steve’s apartment is on the fifth floor of the building.’ What does 3rd and 5th mean? These are called ordinal numbers.

A number that refers to the position of something in a given list of objects or things is referred to as an ordinal number.

Illustration 1

The teacher asks each student in a class of five to identify the ordinal number/position of each animal in the list. Refer to the image above. She drew a table on the board and recorded each student’s responses.

 Item Position (from left) Position (from right) Tiger First Fifth Giraffe Fifth First Elephant Third Third Crocodile Fourth Second Zebra Second Fourth

You’ll notice that each animal in the list is assigned a number that corresponds to its position which in turn depends on the direction of counting them.

Illustration 2

If the arrangement of sharks is from top to bottom then, can you match each shark’s position with the ordinal number? One is done for you in the image shown below.

You’ll see that the shark at the top is in position 1 has the ordinal number “First” marked in the diagram. Similarly, each shark can be identified by comparing its position to its ordinal number, as shown in the diagram.

Try it yourself!

In the list below, write the ordinal numbers that correspond to the colored objects. Keep in mind that you must only consider the colored image.

## Math Facts

• Ordinal numbers was first used in the set theory by George Cantor in his extension theory of the whole numbers.
• Ordinal numbers use the suffix to the numbers: ‘nd’, ‘st’, ‘rd’, or ‘th’. For example: First, Second, Third, Fifth.
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Know more about other concepts of Number Sense on Rounding Numbers, Comparing Numbers, Counting Numbers, Number Line and Cardinality

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