Grammar: Can I start a sentence with a number?

When you start a sentence with a number, you should always spell it out rather than use the numeral. Nineteen thousand people died in the great epidemic. NOT 19,000 people died in the great epidemic.

Yes, you can start a sentence with a number. No grammar rule exists to repudiate this. It's a matter of style as to which you prefer.

Can you imagine the following number written out?

418,812 Mustangs were produced by Ford in the first full year of production.

Would it make sense to write, " Four hundred eighteen thousand eight hundred twelve Mustangs were produced by Ford in the first full year of production."

I wonder Associated Press Handbook would say? for emphasis, I would rather write 5 or 6 people died. It stands out in a newspaper and takes less space. But I bet it say to write Five or six people.............?????

Yes. For example, "9 Christmas trees were sold at Target yesterday."

I would write it out - as you should for all numbers below ten

Two is company: three is a crowd.

Yes. Numbers are adjectives.

"Five birds are sitting on the roof." is an example.