An ordinal number tells the position of something in a line or list. It answers the question “which one?” Words like first, second, and third are ordinal numbers. Their short forms are 1st, 2nd, and 3rd.
What Is an Ordinal Number?
Picture the end of a race. Three friends run toward the finish line. Mia gets there first. Leo gets there next. Ana comes in after Leo.
The words first, second, and third tell the order in which the friends finished. Those words are ordinal numbers.
An ordinal number names the position of one thing in a sequence. It does not tell how many things there are. It tells which place each thing holds: first place, second place, third place.
3 Cookies or the 3rd Cookie?
Cardinal numbers and ordinal numbers look alike, but they answer different questions. Cardinal numbers answer “how many?” Ordinal numbers answer “which position?”
| Question | Number type | Example |
| How many cookies are on the plate? | Cardinal | 3 cookies |
| You ate three cookies. Which one was the last? | Ordinal | the 3rd cookie |
| How many runners are in the race? | Cardinal | 5 runners |
| Who won the race? | Ordinal | the 1st runner |
Say the two sentences out loud: “3 cookies” and “the 3rd cookie.” The first tells an amount. The second points to one cookie in a line.
How to Write Ordinal Numbers
Ordinal numbers have two forms. Write the word: first, second, third. Or write the number with a short ending: 1st, 2nd, 3rd. That short ending is called a suffix.
Most numbers take -th:
4th, 5th, 6th, 7th, 8th, 9th, 10th, 20th
Three endings break the pattern:
- Numbers ending in 1 take -st: 1st, 21st, 31st
- Numbers ending in 2 take -nd: 2nd, 22nd, 32nd
- Numbers ending in 3 take -rd: 3rd, 23rd, 33rd
Now the twist. The numbers 11, 12, and 13 always take -th: 11th, 12th, 13th. The same goes for 111th, 112th, and 113th. When you see a teen number, skip the 1-2-3 rule and use -th.
1st to 10th: Your Reference Chart
| Short form | Word form |
| 1st | first |
| 2nd | second |
| 3rd | third |
| 4th | fourth |
| 5th | fifth |
| 6th | sixth |
| 7th | seventh |
| 8th | eighth |
| 9th | ninth |
| 10th | tenth |
Keep this chart where you can see it. It settles most spelling arguments fast.
Watch the Spelling
Some ordinal words change their spelling instead of just adding -th:
- first (not “oneth”)
- second (not “twoth”)
- third (not “threeth”)
- fifth: drop the “ve” in five
- eighth: add only “h” to eight
- ninth: drop the “e” in nine
- twelfth: the “ve” in twelve becomes “f”
Read each pair out loud. The spelling looks strange, but the sound stays close to the counting word.
Common Mistake: Start Counting From the Same End
Common Mistake: mixing up 3 and 3rd, or counting from the wrong end. “3 ducks” tells how many ducks there are. “The 3rd duck” points to a single duck: the one sitting in the third spot.
Position also depends on where you start. In a line of five friends, Maya is 2nd from the front but 4th from the back. Before you name a position, check which end you are counting from.
Try It: The Line-Up Switch
Ask five children to stand in a line. Point to each child and have the group call out the position: 1st, 2nd, 3rd, 4th, 5th.
Now ask the 2nd and 4th children to trade places. Ask the group: who is 2nd now? Who is 4th? What changed, and what stayed the same?
The children moved, but the positions stayed put. That is the big idea. Ordinal numbers name spots in a line, not the children standing in them.
Quick Practice
Seven toy cars line up for a race. The blue car wins. The green car finishes next. The red car finishes after the blue and green cars but before the yellow car. What place is the red car in?
Answer: 3rd. The order is blue (1st), green (2nd), red (3rd), yellow (4th).
Related Terms
Explore number line.
Frequently Asked Questions
Why is it 11th and not 11st?
The numbers 11, 12, and 13 are the teen exception. They always take -th, no matter what their last digit is. So we write 11th, 12th, and 13th.
What is the difference between 3 and 3rd?
3 is a cardinal number. It tells how many: 3 apples. 3rd is an ordinal number. It tells position: the 3rd apple in the row.
Is there an ordinal number for zero?
The word “zeroth” exists, but we almost never use it in elementary math. Ordinal numbers in the classroom start at first.
When do we write “first” and when do we write “1st”?
In stories and full sentences, write the word: “She finished first.” In lists, dates, scores, and charts, the short form is common: “1st place,” “May 1st.”
The next time you stand in the lunch line or check the date on the calendar, listen for the order words. First, second, third. They are small words, but they keep the whole line in order.