Generally speaking, when we see a number before a noun, the noun is in the plural case. However, it must be remembered that nouns preceded by a number are sometimes used before other nouns. Some examples of correct and incorrect usage include:
wrong |
right |
alternative right |
| a two legs animal | a two-legged animal | an animal with two legs |
| a three stars hotel | a three-star hotel | . |
| a four hours class | a four-hour class | a class of four hours |
| a 100 dollars bill | a 100 dollar bill | . |
| a million miles journey | a million-mile journey | a journey of a million miles |
A few other points to consider:
Rule: |
Example: |
| a) they start a sentence. | Nineteen students came to class yesterday. |
| b) they are less than 10 (unless they refer to a measurement, money or time). | At 7 PM the 7-inch hats were sold for $7 at all seven stores. |
| c) they follow another spelled out number. | Forty or fifty people attended the party. |
| d) they are a fraction. | Four-fifths of the earthıs surface is covered with water. |
| e) they precede a compound adjective between 1 and 100. | Make that seventy 7-inch hats were sold. |
Rule: |
Example: |
| a) they are 10 or over. | Last year, 52 employees at our company achieved their goal on the TOEIC. |
| b) refer to measurements, money or time. | I heard that 2 hours ago they sold 750 ml Bottles of wine for 5 yen to celebrate their anniversary. |
| c) they are addresses (except One) | 1600 Pennsylvania Avenue is a fairly famous address. |
| d) they are statistical; percentages, percentiles, proportions, etc. | Anyone with a test score in the upper 2 percentile may apply for membership in Mensa. |
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