I want to write a program which will translate a number into text, but I am not sure how to read those numbers and about the rule.

999,999 =?

  1. Nine hundred ninety nine thousand and nine hundred ninety nine?
  2. Nine hundred and ninety nine thousand and nine hundred ninety nine?

123,909,909 =?

  1. one hundred twenty three million nine hundred nine thousand and nine hundred nine?
  2. one hundred and twenty three million nine hundred nine thousand and nine hundred nine?

1,000,000,000,000,000 =?

  1. one million billion?

What is the rule to read them?

  • 1
    By the way, the word and in math means a decimal. Don't say and in your three examples. Jan 31 '15 at 23:33
  • 2
    @Bob-the-zealot -- My teachers discouraged the use of "and" in similar contexts, but I don't think it was for the reason you suggest. To my (American) ear, it seems natural for people to put an "and" or "'n" between the word "hundred" and the tens' place of the number. ell.stackexchange.com/questions/1144/… has more discussion of this issue.
    – Jasper
    Jan 31 '15 at 23:41
  • When my wife interviews other computer programmers, she often asks them to write a program that solves this problem. (The input to the function is a number that can be represented by a non-negative integer in Java: {0, 1, …, 2³¹-1}; the output is a String.) As you point out, it helps to know how native speakers of English expect these numbers to be said.
    – Jasper
    Jan 31 '15 at 23:49
  • @Jasper, OK, I'm Canadian. That's why, probably; :) Jan 31 '15 at 23:50
  • A similar question is: ell.stackexchange.com/questions/30350/…
    – Jasper
    Feb 1 '15 at 0:55

Avoid saying "and" in the middle of a number

Bob the zealot is correct that you should avoid saying "and" in the middle of numbers. It is common for Americans to include "and" or "'n" in the middle of a number, especially after the word "hundred". American grade school math teachers discourage this, because it is unclear whether the student has stated a number, or stated a math problem.

As Bob the zealot suggests, you usually should say "and" between a whole number and a fraction. For example, 1½ = "one and a half"; 1.5 = "one point five"; 1¾ = "one and three quarters"; 1.75 = "one point seven five" or "one point seventy five". Similarly, $ 1.75 = "a dollar seventy five" or "one dollar and seventy five cents". Dollars and cents are discussed in another ELL post.

Big round numbers

There are a few different ways to say numbers like 1,000,000,000,000,000.

This number can be unambiguously expressed as "ten to the fifteenth", or less formally as "one followed by fifteen zeroes". Unfortunately, this is not the usual name for the number.

Americans usually express this number as "a quadrillion"; I am told that British speakers used to call it "a thousand billion" (and some still do).

Americans will correctly understand "a million billion"; I am told that some British speakers will think that you mean 1,000,000,000,000,000,000 instead.

Americans use the sequence: thousand, million, billion, trillion, quadrillion, quintillion, sextillion, septillion, octillion, nonillion, decillion, ….

I am told that the corresponding British sequence was: thousand, million, thousand million, billion, thousand billion, trillion, thousand trillion, quadrillion, thousand quadrillion, quintillion, thousand quintillion, ….

I list several ways Americans express large numbers in this Math Educators.Stack Exchange answer: https://matheducators.stackexchange.com/questions/4448/math-activities-for-gifted-second-and-third-grade-math-circle-students/6097#6097

Sizes.com has a history of big numbers, with citations.


The original post uses examples of most of the words in typical large numbers: units (like "one" or "two"), tens (like "ten", "twenty", "thirty"), hundreds, and large round numbers. The numbers between eleven and nineteen are a bit weird:

  • "eleven" = 11
  • "twelve" = 12
  • "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", and "nineteen" are 13, 14, 15, 16, 17, 18, and 19 respectively.


Here is how I say the original poster's examples. As Cort Ammon suggests, there is a pause before each triplet of digits. I have indicated the pauses with commas:

999,999 = "Nine hundred ninety-nine thousand, nine hundred ninety-nine"

123,909,909 = "One hundred twenty-three million, nine hundred nine thousand, nine hundred nine"

  • 1
    Excellent answer. I would like to add that, in addition to not using "and," English speakers will often pause between groups of 3 digits (thousands, millions, etc). Not only does this replace the need for "and," but gives a listener time to process the units. If I say "three hundred five thousand .. twenty one," a listener doesn't know what digits 305 is in, until we hear the word "thousand." The pause gives us time to mentally turn 305 into 305,000
    – Cort Ammon
    Feb 1 '15 at 3:57
  • And if you are writing a check, you don't use "and" till you get to the last "and zero/100~~~" (where the / is actually horizontal), to indicate how many cents are to be paid. Then you add squiggles to the end of the underscore to make it harder for the check's value to be altered. :)
    – A.Beth
    Feb 1 '15 at 5:17
  • 1
    Excellent answer. Here are a few corrections/additions to consider. Americans don't understand "a million billion". Americans usually say: 100 = "a hundred"; 101 = "a hundred 'n one"; 1,000 = "a thousand"; 1,001 = "a thousand and one"; 100,000 = "a hundred thousand"; 1,000,000 = "a million"; etc. "One point seventy-five" is rare. My British friends tell me that the British switched to the American meanings of "billion", "trillion", etc. long ago (not so long after the Science Fiction sketch).
    – Ben Kovitz
    Feb 1 '15 at 6:14
  • 4
    Good answer - except for one thing... In BrE it is "nine hundred and ninety nine thousand, nine hundred and ninety nine" "One hundred and twenty three million…" etc. It always sounds odd to a UK ear when Americans miss out the 'and', though we're getting more used to it in recent years, as the pond gets narrower;) Agreed, though - BrE gave up trying to insist on the 'true' billion of 1 million million & gave in to the US thousand million a long time ago. Feb 1 '15 at 13:03

Use "and" between the word "hundred" and the "tens/units":

345= three hundred and forty-five.

9909999 = nine million, nine hundred and nine thousand, nine hundred and ninety-nine.

In case that the hundreds digit is zero, you place "and" before the tens/hundreds

1001 One thousand and one.

7021034 Seven million, twenty-one thousand and thirty-four.

123,909,909 = one hundred and twenty-three million, nine hundred and nine thousand, nine hundred and nine.

1,000,000,000,000,000 = one quadrillion, though "a million billion" would be possible.

Very large numbers like this don't occur outside of science (and economics?) and standard scientific form is usually preferred, this would be ten-to-the-power-fifteen in speech and 1×10¹⁵ in writing.

In some (mostly "school math" contexts or when writing a "check" in the USA) the word "and" is omitted. This is acceptable, but less common, especially in the UK.

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