NumbersThe international number system: millions and billions
Most of the world, and all of science, groups large numbers in threes: thousands, millions, billions, trillions. School books in India call this the international system of numeration. You meet it in world population figures, company results in dollars, computer storage and on every calculator.
The place values
Each new name comes after three more digits.
| Hundred millions | Ten millions | Millions | Hundred thousands | Ten thousands | Thousands | Hundreds | Tens | Ones |
|---|---|---|---|---|---|---|---|---|
| 5 | 4 | 3 | 2 | 1 | 6 | 7 | 8 | 9 |
The number shown is 543,216,789.
One million is a thousand thousand: 1 followed by 6 zeros. One billion is a thousand million: 9 zeros. One trillion is a thousand billion: 12 zeros.
Periods and commas
The periods are ones, thousands, millions, billions and trillions, and every period has exactly three places: ones, tens and hundreds of that period. A comma goes after every three digits from the right.
54,321,678 = 54 million 321 thousand 678
Reading a number
- Put in commas every three digits from the right.
- Read each group as a number up to 999 and say the period name after it.
- Skip any group that is all zeros.
Example: 7,005,409 is "seven million five thousand four hundred nine". And 30,000,025 is "thirty million twenty-five".
"And" or no "and"?
British and Indian English say "four hundred and nine". American English says "four hundred nine". Both are correct. School books in India mostly write number names without "and", so follow your teacher. Our converter has a tick box for it.
The same word, two meanings
Today "billion" means a thousand million everywhere in English. In older British books it meant a million million. If you read something printed before the 1970s, or translated from a European language, check which is meant. In this site billion always means 1,000,000,000.
Spaces instead of commas
Scientific writing often uses a thin space instead of a comma: 54 321 678. This avoids confusion with countries that use a comma as the decimal mark. The grouping is still in threes.
Short forms
K stands for thousand (from kilo), M for million and B or bn for billion: 5K, 2.5M, 1.2B. In money news you may also see "mn" for million. In India you will see "L" or "lac" for lakh and "Cr" for crore.
Moving between the two systems
The quickest bridge is to remember three facts.
- 1 million = 10 lakh
- 10 million = 1 crore
- 1 billion = 100 crore
So 3.5 million is 35 lakh, 40 million is 4 crore, and 2 billion is 200 crore. The full table, with zeros, is on the lakh, crore, million, billion page, and the Indian number system has its own page.
Common mistakes
- Reading 1,000,000 as ten lakh one moment and "one million thousand" the next. Decide which system you are in before you read.
- Hundred thousand. The international system has no single word for 100,000. It is "one hundred thousand".
- Too many or too few zeros. Count the groups: million has two groups of three zeros, billion three, trillion four.