Associated Topics || Dr. Math Home || Search Dr. Math

### Commas in Numbers

```
Date: 09/13/2001 at 21:44:17
From: LaToya Clayton
Subject: Do commas change the value of a number

Why are we taught in grade school to put the comma after the third
digit in a large number? (9,876,543,210). Why not the fourth digit?
(98,7654,3210). And does the comma really change the number value?
```

```
Date: 09/13/2001 at 23:28:50
From: Doctor Peterson
Subject: Re: Do commas change the value of a number

Hi, LaToya.

The comma has no effect on the value of a number. All it does is make
it easier for humans to read it. We put a comma every three digits to
match the way we say numbers in English, by thousands. Your number

9 billion, 876 million, 543 thousand, 210

Divided every four digits, you would want to read it as something like

(I made up the word "myrion," but "myriad" really does mean "ten
thousand".)

The commas are purely for convenience.

- Doctor Peterson, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics: