1st, 2nd, 3rd, 4th, 21st, 22nd, 33rd

These numbers are called ordinal numbers.

Why do we spell 1st, 2nd, 3rd, 4th like this?
Where do the letters come from?

In this lesson, we're looking at the spelling of ordinal numbers and a few rules.

1st = first (She won first prize.)
2nd = second (I live on the 2nd floor.)
3rd = third (Take the third turning on the left.)
4th = fourth (It's his fourth birthday.)
5th = fifth (This is the 5th time I've taken my driving test.)

We need to write these ordinal numbers in words in formal writing - business, job applications, etc. But it's OK to write them in numbers (1st, 2nd, 3rd...) in informal writing to friends, colleagues, social media comments, etc.

Look at these and notice the last two letters of the words
1st = first
2nd = second
3rd = third
4th = fourth
5th =fifth

Can you see the last two letters of the words make up the ordinal number?
first - last two letters are 'st' so put after 1 = 1st
second - last two letters are 'nd' put after 2 = 2nd
third - last two letters are 'rd' so put after 3 = 3rd
4th - last two letters are 'th' so put after 4 = 4th

We just add 'th' to teen numbers:
14th = fourteenth (fourteen + th)
15th = fifteenth (It's her fifteenth birthday.)
16th = sixteenth
17th = seventeenth
18th = eighteenth
19th = nineteenth

Hyphens for Normal Numbers and Ordinal Numbers from 21 upwards
We need a hyphen when we write cardinal numbers from 21 upwards. Notice there's no space between the letters and hyphen:
twenty-one
twenty-two
thirty-three
sixty-seven
one hundred and twenty-nine
one thousand two hundred and thirty-one pounds

Using a hyphen also applies to ordinal numbers from 21st.
twenty-first = 21st (It's her 21st on Sunday.)
twenty-second
twenty-third = 23rd
thirty-second = 32nd
thirty-third = 33rd
forty-third = 43rd
forty-fourth = 44th
fifty-third = 53rd
fifty-fifth = 55th
sixty-fourth = 64th
sixty-sixth = 66th
seventy-eighth = 78th
seventy-seventh = 77th
eighty-second = 82nd
eighty-eighth = 88th
ninety-ninth = 99th
two hundred and twenty-first = 221st
Remember, no space between hyphen and words.

Spelling rules with whole numbers - 20th, 30th, 40th...
20th = twentieth We have twenty and change the 'y' to 'ie' and add 'th' = twentieth (My birthday is on the 20th)
30th = thirtieth (It's her thirtieth birthday.)
40th = fortieth (It's my 40th birthday tomorrow.)
50th = fiftieth
60th = sixtieth
70th = seventieth
80th = eightieth
90th = ninetieth

In long numbers, 'th' is added to the last number:
106th = one hundred and sixth
242nd = two hundred and forty-second
2018th = two thousand and eighteenth

Careful
four, fourteen, forty (drop the u) and fourth, fourteenth, fortieth

five, fifteen, fifty and  fifth, fifteenth, fiftieth ( the 'f' helps pronunciation)

nine, nineteen, ninety but ninth (drop the 'e'), nineteenth, ninetieth (keep the ‘e’)

twelve but twelfth (Notice the 'v' becomes 'f')

Now do the exercise below