Numbers from one to nine are usually written as words; numbers 10 and over are usually written as numerals.
two six 12 36 144 1,760
Except: Numbers being compared should be kept in the same style.
The cast of Scrooge has actors from ages 8 to 88.
Very Large Numbers
You may use a combination of numbers and words for very large numbers.
342 million 14 trillion
Use words, not numerals, to begin a sentence.
Twelve students signed up for the park cleanup day.