mama25angels Posted September 17, 2010 Share Posted September 17, 2010 decimals when changing them to fractions. I'm helping my DS with this and just can't explain it to where he gets it. Thanks, Here's an example of a problem: .1333..... we get how to change it to a fraction just not doing a great job on simplifying it. Quote Link to comment Share on other sites More sharing options...

Martha in GA Posted September 17, 2010 Share Posted September 17, 2010 (edited) Because 0.13333 has a single repeating digit (3), multiply the repeating decimal by 10 (if you had 0.464646, then you have two repeating digits (46) and you would multiply by 100, etc.). Then subtract the two numbers: 10 x 0.13333 = 1.33333 1 X 0.13333 = 0.13333 9 x 0.13333 = 1.2 Dividing both sides by 9: 0.13333 = 1.2/9 Multiplying top and bottom by 10 to get rid of the decimal, 0.13333 = 12/90 Simplifying, 0.13333 = 2/15. I hope this formats correctly AND is helpful! Oops: I see you already got the fraction and you need help simplifying the fraction? 12/90: dividing both top and bottom by 6 gives the 2/15 Martha Edited September 17, 2010 by Martha in GA additional info. Quote Link to comment Share on other sites More sharing options...

mpcTutor Posted September 17, 2010 Share Posted September 17, 2010 decimals when changing them to fractions. I'm helping my DS with this and just can't explain it to where he gets it. Thanks, Here's an example of a problem: .1333..... we get how to change it to a fraction just not doing a great job on simplifying it. For solution see: How to represent a recurring decimal number as a rational number. Best regards. MPCtutor http://www.mpclasses.com/ContactUS.htm ---------------------------------------------------------- AP Calculus, AP Physics, IIT JEE Test Prep. ---------------------------------------------------------- US Central Time:1:28 PM 9/17/2010 Quote Link to comment Share on other sites More sharing options...

Teachin'Mine Posted September 17, 2010 Share Posted September 17, 2010 To give an example from Saxon Algebra II, here's the system they use: .01623232323 (in other words with the bar over the 23) To convert it to a fraction: In the number above, we will refer to .1623 as N Take 100N = 1.623 Subtract N = .01623 Difference: 99N = 1.607 N = 1.607 / 99 Multiply numerator and denominator by 1000 N = 1607 / 99,000 _________________________________________ In the case of three repeating numbers such as 1.031543543543 (543 are the repeating numbers) the same is done, but the number is multiplied by 1000 1000N = 1003.1543 Minus N = 1.0031 999N = 10002.1512 divide both sides of the equation by 999 N = 1002.1512 / 999 Multiply numerator and denominator by 10,000 N = 10,021,512 / 9,990,000 HTH Quote Link to comment Share on other sites More sharing options...

LoriM Posted September 17, 2010 Share Posted September 17, 2010 Honestly, if you get *how* to turn it from a repeating decimal into a fraction, you are doing better than 98% of the free world. I'd accept unsimplified forms of those fractions, particularly for crazy ones like Teachin' Mine's example of N = 10,021,512 / 9,990,000 which could certainly be simplified by dividing by 2 or 4 or maybe even 8 (LOL), but goodness, it's enough that the kid got the problem IMHO. LoriM (who has to look up that procedure EVERY YEAR I teach it! LOL!) Quote Link to comment Share on other sites More sharing options...

April in CA Posted September 17, 2010 Share Posted September 17, 2010 Wow! Thanks for this nifty bit of information! Blessings, April Quote Link to comment Share on other sites More sharing options...

## Recommended Posts

## Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.