Ordinal Numbers

For Elementary Students

What Are Ordinal Numbers?

Ordinal numbers tell you the position or order of something.

Think about it like this: If you're standing in line for lunch, are you the first person? The second? The fifth?

Regular numbers (1, 2, 3) are called cardinal numbers — they tell you "how many."

Ordinal numbers (1st, 2nd, 3rd) tell you "which one in order."

The First Ten Ordinal Numbers

Pattern: Most ordinal numbers end in -th, but 1st, 2nd, and 3rd are special!

Using Ordinal Numbers

In a race:

• "I came in 1st place!" (You won!)
• "She finished 3rd."

In line:

• "I'm the 5th person in line."

Floors in a building:

• "My classroom is on the 2nd floor."

Dates:

• "My birthday is January 15th."

Writing Ordinal Numbers

The short way to write ordinals uses the number plus two letters:

• 1st (first)
• 2nd (second)
• 3rd (third)
• 4th (fourth)
• 5th (fifth)

Rule: Add the last two letters of the word.

For Junior High Students

Ordinal Numbers Beyond 10

The pattern continues:

The Pattern for Larger Numbers

For numbers ending in 1, 2, or 3 (except 11, 12, 13):

• Numbers ending in 1 → use st (21st, 31st, 41st)
• Numbers ending in 2 → use nd (22nd, 32nd, 52nd)
• Numbers ending in 3 → use rd (23rd, 33rd, 63rd)
• All others → use th (24th, 25th, 30th, 100th)

Exception: 11th, 12th, and 13th use th (not 11st, 12nd, 13rd).

Real-World Uses

Calendars and Dates:

• "The concert is on May 7th."
• "School starts September 1st."

Rankings:

• "Our team finished in 3rd place."
• "This is the 12th largest city."

Sequences:

• "This is my 4th time visiting."
• "Read the 5th paragraph."

Fractions Connection:

• 1/4 is "one fourth" (ordinal!)
• 1/5 is "one fifth"
• 3/8 is "three eighths"

The bottom number (denominator) uses ordinal language!

Cardinal vs. Ordinal

Cardinal = counting/quantity Ordinal = position/order

Ordinal Numbers in Math

Ordinals help us describe:

• Sequences: "Find the 10th term in the pattern."
• Lists: "What's the 5th number in this list?"
• Steps: "Complete the 1st step, then the 2nd step."

Practice