When writing out large numbers in words, should commas be placed at thousand separators?

Question

Would a number, say,

5,629,296

be written with commas:

Five million, six hundred twenty nine thousand, two hundred ninety six

or without commas:

Five million six hundred twenty nine thousand two hundred ninety six

Answer 1

It's a style guide thing in my op, but if you're writing out numerals that large in a block paragraph, I would recommend using the commas for readability purposes - a string of text numerals is hard to parse - and it also sounds better (I'm relatively sure most people insert pauses between logical digit groupings).

I'll admit to influence being ex APS (Australian Public Service), but we do tend to do a lot of writing and our style guidelines have been hammered out specifically with a view to making sure that the relevant information gets to the eyes of the target reader, in a form with the lowest chance of it being mangled.

Paraphrasing our guide (specific reference below) and personal experience, three other suggestions:

• If you can, place the numeric form after the string. The numbers are much easier to scan for in text, and give a quicker indication of 'sizeness'.

  five million, two hundred and fifty thousand, four hundred and twenty-two (5 250 422)

• I'd also suggest retaining the and within digit blocks. In my op, it's more natural but also binds the numerals together indicating who belongs to which group.

  four hundred and twenty-two

  not

  four hundred twenty two

• Finally, hyphenate between the tens and ones of a group of digits, again for readability.

  two million, fifty-four thousand, nine hundred and ninety-nine.

  not

  two million, fifty four thousand, nine hundred and ninety nine.

I thought it was a bit silly when first having to internalise the style guide, but after a while it starts to make sense, for example in a straight side-by-side:

Five million six hundred twenty nine thousand two hundred ninety six

Five million, six hundred and twenty-nine thousand, two hundred and ninety-six (5 629 296)

Of course, your internal guides (or the prevailing style in your area, I have a funny feeling AmE might drop the internal ands for instance) will have their own suggestions, and consistency is king with something like this.

Source: Old habits from a stint in the Australian Public Service as a policy officer, and the Style Manual (6th ed), pg 176. (ISBN 978-0-7016-3648-7)

Answer 2

I think this is a question of readability. From my own experience the use of commas and the breaking up of the numbers into groups of three is optional, however in some ways has become a convention. When converting this into text, the same would apply. In most cases, spelling the number with the same commas as used when in numerical form facilitates readability. The only case where this may become confusing is if you were listing large numbers in a sentence, in which case leave them out.

Answer 3

I think the general consensus with this is whatever makes it easiest and clearest for the reader to understand.

Thus:

Five million, six hundred and twenty nine thousand, two hundred and ninety six.

Answer 4

"Two hundred and ninety-six" or "two hundred and fifty thousand" are both wrong. In the first example, the "and" denotes a decimal point. Converted properly into digits it would be: 200.96. In the second example, the "and" serves as a plus symbol. Converted properly into digits it would be: 200 + 50,000. The word "and" has no place in a properly written or spoken whole number. The commas should be placed like they would be when written out as digits. Ex: One hundred eleven million, one hundred eleven thousand, one hundred eleven would be 111,111,111.