Confused with ... numbers?

Here’s a quick guide:

Write one to ten in words and then use numerals, except if in the same sentence:
❌ My LI post was liked by nine but viewed by 56
✔️ My LI post was liked by nine but viewed by fifty-six (don't forget the hyphen between tens and units)

If writing about ages, always write in numerals but don’t forget to hyphenate:
❌ The oldest person in the world is 117 years old
✔️ The 117-year-old man is the oldest person in the world

Temperatures should be written as an abbreviation with the degree symbol and no space:
❌ 46 degrees C
✔️ 46˚C

Years should be elided using the en (long) dash:
❌ 1921-1922
✔️ 1921–1922

Page numbers should be elided using the en dash:
❌ pp. 345-6
✔️ pp. 345–6

It’s always better to write decades in full unless the century is very clear:
❌ The ‘40s and ‘50s
✔️ The 1940s and ‘50s
And no apostrophe before or after the s!
❌ Life in the 40’s …
❌ Life in the 40s’ …
✔️ Life in the 1940s …

When writing about ‘centuries’, remember when to hyphenate. Compounds used as adjectives should be written with a hyphen:
❌ The eighteenth-century was a time of revolution
✔️ The eighteenth-century revolutions ...