1. For Numbers 10 and Greater
For numbers 10 and greater, use numerals and spell out numbers one through nine.
Examples:
My laptop was purchased three years ago.
There are 366 days in a leap year.
There are, however, some exceptions to the rule...
MONEY:
10 cents, $50, 25 paisa, €100
TEMPERATURES:
25 degrees
HIGHWAYS:
Route 30, Route 66
ADDRESSES:
2677 Pine Garden Lane
AGES (for people and objects):
9-year-old computer, 6-year-old buy
DIMENSIONS:
12 feet deep
Also Read:
MILLIONS, BILLIONS:
10 million subscribers. The population of the world is 8 billion.
2. At the Beginning of the Sentence
Numbers at the beginning of sentences should be spelled out in full rather than used as a numeral.
Examples:
Fourteen trekkers finally made it to the top of the mountain.
Thirty-two employees were granted promotions this year.
DO NOT write: 32 employees were granted promotions this year.
This also means that if it is a large number, you may need to rewrite the sentence to improve clarity. E.g. Instead of Two hundred and fifty thousand copies are available for sale, change it to There are 250,000 copies for sale.
3. In Headings and Titles
For headings and titles, it is preferable to use the numeral instead of spelling it out, whether at the beginning of the sentence or not.
Examples:
2022 was a year of revival for the travel industry
10 Great Tips for Writing
Top 10 Reasons Why Should Drink Water in the Morning
25 Best Science Fiction Movies of All Time
Meditation Is Good for You Body and Mind: Here Are 10 Benefits
4. Dates - The Rules
Date and Time Should Be Ordered Chronologically, Beginning with the Hour
Examples
9 a.m., November 10, 2022
11 p.m., January 1, 2010
Use Numbers for Days of the Month
You can use a cardinal (10) or an ordinal (10th) number to write the day of the month.
Examples:
I have heard that she was born on December 25.
The joining date is on the 3rd of October.
Use Numbers for the Full Date
You can use numbers for the month, day, and year when writing out the whole date. You can also spell out the month and use numbers for the day and year.
Examples:
The trip is planned on November 15, 2023.
Be there for the party: 05/07/2023
Exception: Do not use ordinal numbers when using full dates. E.g., June 19th, 2022 is WRONG!
Days of the Month
Incorrect: April 10st, October 9th, June 2nd
Correct: April 1, October 9, June 2
Punctuation
The finale is scheduled for Monday, March 27, 2023, at the National Stadium.
The music festival will run month-long on October 2023 at the Carnation Hall.
Decades and Centuries
The ‘70s have been a year of transformation for the music industry.
INCORRECT: The 70s have been a year of transformation for the music industry.
The 1970s have been a year of transformation for the music industry.
DO NOT USE 1970’s!
Inclusive Years
2020-30
2099-2100 (example of century change)
5. Time - The Rules
It is now commonly accepted to refer to time in numerical form.
Examples:
I have a meeting at 9:30 a.m.
The train will depart at 5:15 p.m.
Interestingly, some writers like to spell out the time.
Example:
She has the six-thirty bus to catch.
My training starts at seven o’clock in the afternoon.
At the top of the hour, the time is written as a single digit without the :00 appended.
Example:
My visit has been scheduled for 7 p.m.
DO NOT write My visit has been scheduled for 7:00 p.m.
Instead of 12 p.m. and 12 a.m., write noon and midnight.
The abbreviations for AM and PM are also written as a.m. and p.m., A.M. and P.M. Generally, people separate the time from the AM/PM with a space.
Examples:
10:15 a.m.
10:15 A.M.
10:15 AM
6. Fractions - The Rules
Fractions should be spelled out and hyphenated.
Examples:
Asia makes up roughly one-third of the landmass.
One-sixth of the book sales come from Australia.
The hole size is three-fourths of the diameter.
Mixed fractions, in most cases, are expressed in numerals unless they begin a sentence.
Examples:
The findings detected a 3 1/5 improvement in performance
The temperature of the machine is expected to fall by 1 2/7 degrees.
Ten and two-thirds percent is an acceptable limit for the engine.
7. Large Numbers - The Rules
For Numbers with Four Digits or More, Use Commas
Place commas after every three digits from the leftmost digit. Note: This does not include the decimal point.
Examples:
The sales from the previous year amounted to exactly $75,125,000, which is a record number.
The stock closed at 3,500.50
However, When Spelling Out Numbers above 999, Do Not Use Commas
Example:
Three thousand four hundred and thirty-two dollars.
DO NOT write three thousand, four hundred, and thirty-two dollars
Large Numbers That Are Rounded or Estimated Should Be Spelled Out as a Combination of Digit and a Word
Example:
The world population is expected to stabilize at 10 billion.
There are over 100 million sound samples in the music library. (instead of 100,520,000 sound samples ...)
Superscripts
The 25th applicant was selected for the coveted post.
Percent
It has been observed that 25 percent of the residents abstained from voting.
The sample's mean deviation was 25% more than was reported.
8. Numbers with Decimals
The decimal point is often preceded by a zero as a courtesy to readers.
Examples:
The machine has a precision of 0.15 millimetres.
She won the race by a margin of 0.5 seconds.
Monetary Amount
A slice of pizza, although very small, was just 50 cents.
My two cents is that we should call an expert.
9. Compound Numbers
All compound numbers between twenty-one and ninety-nine should be hyphenated.
Examples:
Next year, twenty-five students will participate in the student exchange program.
Approximately forty-three employees were given a raise.
10. Use Parentheses to Avoid Misrepresentation
To avoid misrepresenting a number, some writers include spelled-out numbers in parentheses. Do not include the numerals in parentheses.
Example:
We recommend using the 52 (fifty-two) grade material.
DO NOT write We recommend using the fifty-two (52) grade material.
11. Side-by-Side Numbers (Two Numbers Next to Each Other)
Spell out one of the numbers when they appear next to each other in a phrase. Either the number on the right or the left can be spelled out, but be consistent. This avoids confusing the reader.
Example:
The tour company plans to replace 5 ten-year old cars with newer models.
OR
The tour company plans to replace five 10-year old cars with newer models.
INCORRECT: The tour company plans to replace 15 7-year old cars with newer models.
12. Multiple Numbers Used in a Sentence
Whenever there are two or more numbers in a phrase that refers to the same entity or category, and at least one of those numbers must be written as a numeral, all quantities in that category must be written as numerals.
Example:
The report suggests that 3 routers, 10 servers, and 25 computers must be replaced to improve performance.
13. Numbers in a Casual Context
Spell out numbers when they are referred to in a casual context. This applies to ordinal numbers as well (first instead of 1st)
Example:
“Gosh! I’ve repeated this story a hundred times.”
“I was lucky the third time in my relationship.”