Introduction
When writing a nontechnical or a technical paper or essay, there is a high tendency of having to make use of numbers in your text, most especially if you are writing a scientific paper where you would have to report numerical information about your research.
Most authors are fond of spelling out the numbers that can be written in one or two words and then using figures for numbers that would require more than two words to be spelt out. However, the writing format for your paper or essay is what determine how numbers should be written in your text.
Therefore, if you are writing your paper or essay using the Chicago format, the manual states that for technical writing, the simple rule of spelling out only singledigit numbers and using numerals for all others should be followed. However, there are exceptions to this rule, and these exceptions are what we are going to be looking at in this article.
Numbers to Be Spelt out
The following are exceptions where even if the number is more than nine it should be spelt out

Numbers That Begin a Sentence
Numbers should always be spelt out when they begin a sentence. This is done to avoid awkwardness. Even if a year has to begin the sentence, it has to be spent out in full.
For example
305 candidates failed the test
Twentytwenty has been a horrible year so far.

Fractions
Simple fractions are meant to be spelt out for the sake of readability.
For example
Only about onethird of the students passed the exam
Numbers to Be Written in Figures
The following are exceptions where even if the number is between zero to nine it should be written in figures

Ordinals
Ordinals should always be written in figures
For example
She found herself on the 9th floor

Units of measurement
When you are writing a number succeeded by a unit of measurement, the number should be written in figures.
For example
7gb
340 cm

Mixed fraction
Unlike simple fractions when a number is to be written along with a fraction, it should be written in figures
For example
You will need about 5½ yards of the cloth

Percentages
Percentages should be written in figures except when they appear at the beginning of the sentence.
For example
There is a 70% chance of winning with the right strategy
Seventy percent of people that were invited came

Decimal
Decimals should be written in figures, and when a quantity is less than 1.00, a zero should be kept before the decimal point.
For example
The students had a mean score of 45.3
It was in the ratio 0.62

Currency
Currencies and monies should be written in figures except it is an isolated reference to the amount of money
For example
500 dollars
230 pounds

Date
Cardinal numbers are used when writing a date. They should also always be written in the monthdayyear date form or the daymonthyear form
For example
May 2, 2020
11 January 1997

Time
Time should be represented with numerals except for the approximation of time where you write them in words
For example
The time is exactly 10:50 pm
She was told to come by 8: am