基数詞と序数詞とは？

高校入試や定期テストでライティングで頻出なので、英語が書けるように。

基数詞

よくスペルミスする単語

0 zero
1 one
2 two
3 three
4 four
5 five
6 six
7 seven
8 eight
9 nine
10 ten
11 eleven
12 twelve
13 thirteen
14 fourteen
15 fifteen
16 sixteen
17 seventeen
18 eighteen
19 nineteen
20 twenty
30 thirty
40 forty
50 fifty
60 sixty
70 seventy
80 eighty
90 ninety
100 a hundred
1,000 a thousand
10,000 ten thousand
100,000 a hundred thousand
1,000,000 a million
10,000,000 ten million
100,000,000 a hundred million
1,000,000,000 a billion
10,000,000,000 ten billion
100,000,000,000 a hundred billion
1,000,000,000,000 a trillion

序数詞

1番目、2番目、2番目を英語にしたもの。

よくスペルミスする単語

1st first
2nd second
3rd third
4th fourth
5th fifth
6th sixth
7th seventh
8th eighth
9th ninth
10th tenth
11th eleventh
12th twelfth
13th thirteenth
14th fourteenth
15th fifteenth
16th sixteenth
17th seventeenth
18th eighteenth
19th nineteenth
20th twentieth
30th thirtieth
40th fortieth
50th fiftieth
60th sixtieth
70th seventieth
80th eightieth
90th ninetieth
100th (one) hundredth
1,000th (one) thousandth
10,000th ten thousandth
100,000th (one) hundred thousandth
1,000,000th (one) millionth
10,000,000th ten millionth
100,000,000th (one) hundred millionth
1,000,000,000th (one) billionth
10,000,000,000th ten billionth
100,000,000,000th (one) hundred billionth
1,000,000,000,000th (one) trillionth

よく出題される英文法

One in ten people live on an island.
10人中1人が島に住んでいる

Five is my lucky number.
5は私のラッキーナンバーです
＊不可算名詞扱いなので、「is」が使われる。

分数

1/3 one-third
1/5 one-fifth
2/3 two-thirds
2/5 two-fifths
45/81 forty-five eighty-firsts
17/200 seventeen two-hundredths

1/2 、1/4 は、特別な単語がある

1/2
one-half / a half

1/4
one-quarter / a quarter　(主にイギリス英語）
one-fourth / a fourth　（主にアメリカ英語）

3/4
three-quarters / three-fourths

英語の西暦の読み方