Representing numbers: Ordinals

Representing numbers: Ordinals

Lessons

In this lesson, we will learn:

  • How to write ordinal numbers using numbers and superscripts
  • How to write ordinal numbers using words and suffixes
  • How to use ordinal numbers to understand order/ranking/position

Notes:

  • Ordinal means Order
    • Ordinal numbers answer the question “what place/rank/position”?
    • Ordinal numbers are whole numbers only (no fractions nor decimals)

  • Ordinal numbers follow similar rules to the way we write number word names
    • The difference is that ordinals have special endings, or “suffixes
    • When you write ordinals as numbers, these endings are superscripts
      • You write these letters smaller and write them above the normal line
      • i.e. 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, etc.
    • When you write ordinals as words, most ordinal numbers end with “–th” except for numbers that end with 1, 2, or 3 (which use “–st”, “–nd”, and “–rd”, respectively)
      • For multiples of ten from 20 to 90, they end with “–ieth
      • The ordinal 9th is spelled as “ninth” without the e (that is usually in nine)

Representing Numbers: Tally Marks

  • There are 3 types of numbers: Cardinal, Ordinal, and Nominal
    • Cardinal means Counting (ex. there are 6 pool balls)
    • Ordinal means Order (ex. the purple pool ball is in 4th place)
    • Nominal means Name (ex. the green pool ball is labelled “14”)

  • It’s important to know the difference between the word names for written ordinal numbers, written decimals, and written fractions:
    • Ex. 200th is written as two hundredth
    • Ex. 2100 \frac{2}{100} is written as two-hundredths
    • Ex. 0.02 is written as two hundredths
  • Introduction
    Introduction to Ordinal Numbers:
    a)
    What are ordinal numbers?

    b)
    How to write ordinal numbers 1st-100th with numbers and as words

    c)
    How to use the words "before" and "after" when thinking about ordinals

    d)
    What is the difference between cardinal, ordinal, and nominal numbers?


  • 1.
    Identifying Ordinal Numbers
    Circle the ordinal numbers only.
    a)
    85, twenty-nine, 163rd, 42nd, seventeenth

    b)
    Five hundred seventy, 91, 38th, five hundred seventy-first, 2009

    c)
    46th, two thousandths, 681, five hundredth, 709


  • 2.
    Ordinal Numbers and the Alphabet
    a)
    Fill in the chart with letters for the English Alphabet in order.

    b)
    What is the 6th letter of the English alphabet?

    c)
    What is the 15th letter of the English alphabet?

    d)
    What is the 24th letter of the English alphabet?


  • 3.
    Ordinal Numbers and the Months of the Year
    a)
    Fill in the chart with the months of the year in order:

    b)
    What is the 7th month of the year?

    c)
    What order (place) of the year's months is the month of October?

    d)
    What order (place) of the year's months is the month right before April?


  • 4.
    Ordinal Numbers and Ranking (Word Problems)
    Read the sentences to find out the ranking. Write the ordinal number using numbers and words.
    a)
    In a sports car race, right before the finish line, the red race car passed the blue race car. The blue car won second place. What place did the red race car win?

    b)
    At the science fair, Nick's project placed right behind his friend Archie's project. Archie's project won third place. What place did Nick's project win?


  • 5.
    Using Ordinal Numbers to Describe a Picture - 1
    The fruits are ordered in line, starting from left to right.
    Representing Numbers: Tally Marks
    a)
    Which fruit is in the fourth position?

    b)
    Which position is the fruit right before the watermelon?

    c)
    Which position is the fruit right behind the grapes?


  • 6.
    Ordinal Numbers and Calendar Dates
    Look at the calendar for March 3009. Then, answer the questions:

    March 3009

    Sunday

    Monday

    Tuesday

    Wednesday

    Thursday

    Friday

    Saturday

    1

    2

    3

    4

    5

    6

    7

    8

    9

    10

    11

    12

    13

    14

    15

    16

    17

    18

    19

    20

    21

    22

    23

    24

    25

    26

    27

    28

    29

    30

    31

    a)
    What day of the week will the 23rd of March 3009 be?

    b)
    What day of the week will the 8th of March 3009 be?

    c)
    What day will the third Sunday be in March 3009?


  • 7.
    Using Ordinal Numbers to Describe a Picture - 1
    Danny went to visit his local farm. He draws all the animals that he sees on a paper, in order from left to right.
    Representing Numbers: Tally Marks
    a)
    Which animal is in the fifth position?

    b)
    Which position is the animal right before the pig?

    c)
    Which position is the animal right behind the horse?