First, Second, Third, Fourth or 1st, 2nd, 3rd, 4th? One, Two, Three or 1, 2, 3?

Question

When we use words like first, second, third, fourth or 1st, 2nd, 3rd, 4th, in sentences, what will be the best way to write these? Also, what about numbers? Do we put them as numbers or numerals?

Here are some sample sentences,

• He got first/1st class in that examination.
• He gave me two/2 books.
• He will be the first/1st to get there.
• My son is finishing his seventh/7th semester.
• The turkey weighed five/5 Kg.

Yes, I understand that we can have many examples like the above.

Do you think that you can give some general rules for these?

Answer 1

I think it's better to spell out numbers while writing essays or letters or related pieces. (In Mathematics or any Science subject or Commerce subject can one freely use the numbers.)
Also, for giving measurements, The turkey weighed five kilograms seems better than The turkey weighed five Kg. When you are already writing out the number in words, why write the unit in the short form? Spoils the look.

Answer 2

AFAIK, there aren't any set of hard rules about this convention of writing. In practise, I prefer to use the words one, two etc. if I am writing a large paragraph and the numbers are not appearing often enough (opinion-based testing).

In your given examples, I'd use the numerical representation everywhere as the text itself is quite short. Another thing I sometimes follow is, if using words such as first or three; somehow, make the text sound better/rhythmic (it might be hard to explain to English speakers; other languages have different pronunciation for numbers, and I for one, use those when reading) I prefer to compose my text accordingly.

Answer 3

The rule used to be that if the number was less than 10 you would spell it out in a sentence/paragraph. So for the examples above, the first four sentences would all get the spelling version of the number. The last sentence, however, you could be flexible with if it is written in a recipe and everything else has the number. That was how I was taught, but these days ... heck, we can misspell things all day long in an email or text, and it is acceptable.