Usage of "and" and comma when writing numbers UK style?

Question

I am trying to understand the rules for writing numbers in words under the UK rules (with "and"). I understand how to write small numbers (up to a few thousands), but I am not sure when to use "and" when the number is bigger. I tried Wikipedia, but the rules are not clear. Here are a few numbers I'm reasonably sure of: - 102: one hundred and two - 120: one hundred and twenty - 1002: one thousand and two - 1203: one thousand two hundred and three (though I'm not sure whether I should add a comma after "thousand" in this last one). Here are some bigger numbers. Is it okay to have multiple "and"s like this? Should some "and"s be commas instead, or just be omitted altogether? - 102003: one hundred and two thousand and three - 102304: one hundred and two thousand three hundred and four Here are some numbers bigger than one million (I use a space to separate digits for easier reading): - 1 000 002: one million and two - 1 000 020: one million and twenty - 1 000 200: one million two hundred - 1 002 000: one million two thousand - 1 002 003: one million two thousand and three - 1 023 045: one million twenty-three thousand and forty-five - 1 203 450: one million two hundred and three thousand four hundred and fifty And some bigger ones still: - 100 000 300 : one hundred million three hundred - 102 000 003 : one hundred and two million and three - 102 304 567 : one hundred and two million three hundred and four thousand five hundred and sixty-seven

Answer 1

All the numbers over a hundred have "and" in which any unit after the hundred follows the word "and".

21: twenty-one

111: a hundred and eleven (or "one" hundred and eleven)

101: a hundred and one

190: a hundred and ninety

191: a hundred and ninety-one

206: two hundred and six

1,002: a thousand and two

15,726: fifteen thousand, seven hundred and twenty-six

276,521: two hundred and seventy-six thousand, five hundred and twenty-one

1,000,001: a million and one

I also believe for millions it would be something similar to:

102,304,567: a hundred and two million, three hundred and four thousand, five hundred and sixty-seven.

It might be easier to think of the commas as plus signs because you are essentially adding each set of three numbers (102,000,000 + 304,000 + 567).

Hope this helps!