Is it grammatically correct to use numbers instead of words in a sentence?

Technically speaking, it's grammatically correct if you use words for numbers up to 10 in a sentence. Above 10, you should write in numerals only.

Why are so many people stating LIES as facts?

Mamawisdom has the only correct answer here:

"Unless a number starts a sentence, a number between zero and ten should be written in words, a number over ten should be numerical."

Numbers are a problem when they get over a thousand. Because different cultures in the world use different deliminators. Let s take ten million, for example:

U.S. and related countries: 10,000,000

Most of Europe except Switzerland: 10.000.000

Switzerland: 10'000'000

India and other Asian countries use a completely different system that is based on lakh (one hundred thousand) and crore (ten million).

What s still worse, Americans use different words than Europeans for big numbers, an American "billion" is a European milliard.

So to avoid misunderstandings, maybe we all should use scientific notation in powers of ten.

To be honest, I agree with the rule of numbers 0-10 being in words, then anything higher than 10 in numerals. The way I write it though, is words until it gets to something weird and random. I do 'one thousand' but not 'one thousand five hundred and seventy two'. I just keep it nice and simple, but in words (unless it looks ridiculous).

Unless a number starts a sentence, a number between zero and ten should be written in words, a number over ten should be numerical.

It is acceptable but if you are starting off the sentence with a number then is should written in words.

Ex. Correct: One Hundred stars were up in the sky; Wrong: 100 stars were up in the sky.

It is up to you (unless you are using a style manual). Usually single numbers are written as words, anything over ten can be in digits. There is no hard and fast rule except at the beginning of sentences which should be words. Dates are generally written as digits, as are centuries. The only real requirement is to be consistent.

Either is correct and long as one is consistent. Some examples: I am number one and you are number two. With Arabic numerals, it would look like this: I am no. 1 and you are no. 2. Good luck

Up to and including the number ten, you write it out. After the number ten, it's ok to use numbers, and you always use numbers after 100. I got this from Ann Landers, like over thirty years ago. Hope I'm accurate, it's been awhile.

I would answer this question, but I'm offended by your calling me a "Nazi." When you are begging for help from people who are smarter than you are, it's not very useful to begin by calling them mass murderers.

Also, your question has nothing to do with grammar. So you reveal yourself as doubly idiotic by asking whether something that has nothing to do with grammar is "grammatically" correct.