In the international number system, the digits in a number are separated in groups of three starting from the rightmost digit in the number. In another article, we talked about place values and the suffixes that you use to read or write number in the International Number System. If you don’t remember the facts discussed in that article, please read them at the end of the article and then continue from here.

The Indian Number System uses essentially the decimal number system (base-10) but the way numbers are read or written are a little bit different.

In the International Number System, you separate digits in groups of three starting from the far right. Every three digits, you use a separator and then you’ll use suffixes to read the number. The suffixes used in the International Number System (INS) are as follows:

trillion, billion, million, thousand, none

Each of the suffixes listed above are used for three digits separated in a number.

Now, Let’s try an example. Let’s consider the number, “325675723.”

This number in the International Number System is separated as,

235,675,723

and is read as,

Two hundred thirty-five million, six hundred seventy-five thousand, seven hundred twenty-three.

In the Indian number system, you need to separate the digits in the following way:

- The first three digits are separated starting from far right. You don’t need any suffixes for this group.
- The second group of digits would be the next two digits moving towards the left. For this group, you used the suffix, “thousand.”
- The third group of digits would be the next two digits moving towards the left. For this group, you use the suffix, “lakh.”
- The forth group of digits would be the next two digits moving towards the left. You use the suffix, “crore” here.

So the number in the Indian Number System would be separated as,

32,56,75,723

and written in words as,

Thirty-two crore, fifty-six lakh, seventy-five thousand, seven hundred twenty-three.

As you can see, in the Indian Number System, you separate three digits starting from the right and after that, each group contains only two digits all the way up to the last digit of the number (the leftmost digit of the number).

### A More Complicated Example

So now let’s try a larger number: 384476278321

This number in the International Number System would be separated as,

384,476,278,321

and written in words as,

Three hundred eighty-four billion, four hundred seventy-six million, two hundred seventy-eight thousand, three hundred twenty-one.

In the Indian Number System, the number would be separated as,

38,447,62,78,321

Now to write this number in words, we’ll again repeat the suffixes used in the Indian Number System.

- The first three digits have no suffix.
- The suffix used for 78 is “thousand.”
- The suffix used for 62 is “lakh.”
- The suffix used for 47 is “crore.”
- The suffix used for 84 is “arab” but no one uses this suffix very frequently. Here, you use a multiple of crore.
- The suffix for 3 is again a multiple of crore.
- So the number is written in words as, “Thirty-eight thousand, four hundred forty-seven crore, sixty-two lakh, seventy-eight thousand, three hundred twenty-one.

### Observations based on This Example

Please note that, contrary to what you read in the beginning of this article, the separators in the Indian number system are going through periods of 3-2-2. In the beginning of the the number, you start with three digits, and then two two-digit groups and the same cycle repeats itself throughout the whole number. In the beginning of the article, there was no simple way to explain this point.

For your convenience, here’s a list of general numbers and how they are written in words in the Indian Number System:

- 1 = 10^0 (one)
- 10 = 10^1 (ten)
- 100 = 10^2 (hundred)
- 1,000 = 10^3 (thousand)
- 10,000 = 10^4 (ten thousand)
- 1,00,000 = 10^5 (one lakh)
- 10,00,000 = 10^6 (ten lakh)
- 1,00,00,000 = 10^7 (one crore)
- 10,00,00,000 = 10^8 (ten crore)
- 100,00,00,000 = 10^9 (one arab or hundred crore)
- 1,000,00,00,000 = 10^10 (one thousand crore)
- 10,000,00,00,000 = 10^11 (ten thousand crore)
- 1,00,000,00,00,000 = 10^12 (one lakh crore)
- Hopefully you can see the pattern here.

These articles are used by the author in a series of mathematics courses that will teach you mathematics from the sixth standard all the way up to 12th standard. The purpose of these courses are to help us understand mathematics so that you can use them professionally well. There is a road map that we have put together about the all the courses included, where to starts, etc. To know more about that and have access to those courses, please visit mathematics page on Great IT Courses. Thank you.