(Not a problem or a puzzle; just an amusement.)
| 1/1 | 1.0 |
| 1/2 = | 0.5 |
| 1/3 = | 0.[3] |
| 1/4 = | 0.25 |
| 1/5 = | 0.2 |
| 1/6 = | 0.1[6] |
| 1/7 = | 0.[142857] |
| 1/8 = | 0.125 |
| 1/9 = | 0.[1] |
| 1/10 = | 0.1 |
| 1/11 = | 0.[09] |
| 1/12 = | 0.08[3] |
| 1/13 = | 0.[076923] |
| 1/14 = | 0.0[714285] |
| 1/15 = | 0.0[6] |
| 1/16 = | 0.0625 |
| 1/17 = | 0.[0.0588235294117647] |
| 1/18 = | 0.0[5] |
| 1/19 = | 0. [052631578947368421] |
| 1/20 = | 0.05 |
But after doing all this work I then googled...
Posted by DeLong at February 04, 2003 08:05 PM | TrackbackIt's probably more an English problem than a math problem, but on this page it states
"As a matter of fact, every fraction that has an exact decimal equivalent consists only of powers of 1/2, or the product of 1/5 times a power of 1/2 or some multiple of these fractions (such as 3 times 1/4 = 3/4 = 0.75); there is no other way for an exact decimal equivalent to exist."
The key line is "product of 1/5 times a power of 1/2" which should have instead stated "a power of 1/5 times a power of 1/2". Consider 1/25 = 0.04.
An important detail, considering that it's the main point of the web page.
You missed my favorite: 80/81
Posted by: Charles on February 5, 2003 06:23 AMBen Vollmayr-Lee points out that the prime factors of ten, namely 2 and 5, matter when you consider the "does it repeat or terminate?" question. In another base, you'd get a different set of non-repeaters.
In binary fractions, for instance, even tenths are repeating. 1/10decimal = 0.0[0011]binary (hoping I did it right.) This is a peril for the novice accounting programmer, who soon learns that pennies keep disappearing if (s)he represents amounts in units of dollars.
Posted by: John Aspinall on February 5, 2003 07:09 AMIt's fairly easy to generate any repeating decimal you want-- for example,
0.345345345345... = 345/999
Homework problem: find the general formula.
Posted by: Matt on February 5, 2003 07:43 AMMatt, you're giving away the store. Call 0.345_345_ instead 115/333.
-Brian
Posted by: Brian on February 5, 2003 12:03 PMCharles:
It's my favorite too—Pat Metheny, Dewey Redman, Michael Brecker, Jack DeJohnette, and Charlie Haden!
Posted by: David on February 6, 2003 12:44 AM