Rule for writing numbers in writing

Rules for Writing Numbers

There is a lot of confusion regarding numbers in writing. There are different rules for different kinds of writing such as business, technical, mathematical and creative writing. We will restrict ourselves to the rules pertaining to creative writing. However even for creative writing, experts do not often agree with all the rules. 

I will list out the basic rules for creative writing that I have compiled from various sources. 

Rule 1: Spell out small numbers

Single-digit whole numbers less than 10 should be written in word form.

Example:
I would like to order eight cups of tea.

For numbers greater than 9, there is some confusion.

Some experts say that if a number can be written in one word, it should be written out. Two-word numbers should be written as numerals. 

Example:
I would like to buy twenty pizzas.

I bought 24 pizzas. - 24 (twenty four) is a two word number 

Note: In my opinion, it is best to steer clear of all confusion and try to avoid writing numbers in numeral form. For large numbers, see Rule 3.

Rule 2: Do not start a sentence with a numeral.

Example:

Thirty five children died when the school building collapsed.

When the school building collapsed, 35 children died. 

OR (preferable) When the school building collapsed, thirty five children died.

Rule 3: Express large numbers in the simplest way possible.

Spell out rounded numbers. 

Be careful to be consistent within a sentence.

Correct:
You can earn from one lakh to three lakh rupees in a year.

Incorrect:
You can earn from one lakh to Rs. 3,00,000 in a year.

Rule 4: Write simple fractions in word form and use hyphens with them.

Write decimals in figures. Put a zero in front of a decimal. 

Write percentages in numeral form.

Use numeral in recipes.

Examples:
I grew 0.5" last  month.

They ate one-third of the pie. 

More than 20% of the work force is on strike.

Boil 2 cups of water.

Rule 5 : Dates

Examples:
The meeting is scheduled for August 24.
The meeting is scheduled for the 24th of August.

Rule 6: Time

For time, spell out the time of day in text even with half and quarter hours. 

With o'clock, the number is always spelled out.

Use numerals when exact times are being emphasized or when using A.M. or P.M.

Use noon and midnight rather than 12:00 P.M. and 12:00 A.M.

Examples:
She gets up at five thirty.
The baby wakes up at nine o'clock in the morning.

Please arrive by 12:30 sharp.
She had a 7:00 P.M. deadline.