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Post by Random on Nov 11, 2005 1:31:10 GMT -5
actually i find it much easier to visualize pies in decimals, the only reason people have a harder time with that is because people tend to use fractions for that when teaching others
4*.5 requires no special rules.
it is a slightly less easy application of the rules
4 multiplied by .5, is just that, 4 multiplied by .5, which is obviously 2, equally as obvious as the answer to 4*2. the only reason its harder is because it is used less
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Post by Archagon on Nov 11, 2005 1:39:39 GMT -5
i find it much easier to visualize pies in decimals ... ... [silent laughter]
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Post by Arachis on Nov 11, 2005 3:20:03 GMT -5
ok... lets see then how good you are at decimal multiplication without a calculator. Even I have trouble multiplying decimals, while fractions are easy as pi.
quick. 1.732 *4.2
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Post by Archagon on Nov 11, 2005 3:30:19 GMT -5
Okay.
Quickly - what's 9093/1250 as a mixed number?
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Post by Random on Nov 11, 2005 3:35:28 GMT -5
lets see, i'll admit i'm not so hot at math, but thats just me, i'll check my answers once with my brain, and then again with a calculator and display the results seperately
thats (.732*4)+(.732*.2)+4.2 i believe, which isn't too painful
.732*4 = 1.464*2 = 2.928 .732*.2 = .732 / 5 = .1464
so
2.928 + .1464 + 4.2 = 3.0744 + 4.2 = 7.2744
ok, checking with calculator
.732*4 = 2.928 .732*.2 = .1464
1.732 * 4.2 = 7.2744
oh, look at that, same answer
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Post by Arachis on Nov 11, 2005 14:54:44 GMT -5
only because you knew that .2 was 1/5. Thats not really multiplying with decimals thats multiplying with fractions. and why didnt you mention the 1*4.2 until the end?
And alexiess, you never need to turn a fraction into a mixed number until the end of a problem, and even then you hardly ever really need to do it (I almost always leave my fractions whole).
But just for you its 7 & 343/1250.
Just so I can really home in on it, try this problem. 1.45 *3.722 When you are done Ill show you why its twice as fast with fractions.
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Post by Archagon on Nov 11, 2005 16:07:42 GMT -5
Yes, but then of what use is the number? Theoretically, your logic may be sound, but practically - well, unless you think in terms of fractions, you'll need to divide eventually.
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Post by Arachis on Nov 11, 2005 16:32:31 GMT -5
I guess... still its not like its that hard.
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Post by Evilduck on Nov 11, 2005 17:51:53 GMT -5
Dividing is for wimps, always multiply by the reciprocal!
And can you guys stop fighting about preferences? Both fractions and decimals have their own merits.
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Post by Random on Nov 11, 2005 22:26:16 GMT -5
this is not a dispute of preferences, ali and a few others (i think) are as usual disputing my reasons for my opinion if i remember correctly, however i can't quite remember the exact flow of the conversation so someone less lazy can go back and look if they like
and no, i did not remember that .2 = 1/5, i remembered that .2 = 20%
1*4.2 was in the first thing i mentioned, where i sort of divided the parts up, and past then i did not mention it because it was too simple to note
also, ali, i'm getting tired of you making these sad points using a very select example that represents the entire spectrum, you choose equations that specifically do not work as well in decimal form as they do in fraction form specifically because of that, not because they are the majority
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Post by Arachis on Nov 12, 2005 1:49:28 GMT -5
actually choose just about any decimal which goes in the hundreths. The longer the decimal, the easier it is to work with a fractional equivalent, and the only reason you can do short decimals, is because you have essentially memorized what fraction they are.
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Post by Random on Nov 12, 2005 3:11:33 GMT -5
wow i even said that wasn't true and you keep telling me thats how i'm thinking
decimals are easily represented as percents, which makes it very easy for me to think about them
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Post by Arachis on Nov 12, 2005 10:40:41 GMT -5
you still convert percents into fractions. Im almost sure of it. Otherwise, please illustrate for me the process you use to multiply a number by a percent. If you actually multiply by percent I will think about believing you.
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Post by Evilduck on Nov 12, 2005 12:39:47 GMT -5
Why cant you accept that JP has a different way of thinking about math than you Ali? Maybe it is actually easy for him to work directly with decimals and percents but we cant understand it because WE always convert them to fractions?
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Post by Random on Nov 12, 2005 13:48:54 GMT -5
and have never had extended experience trying it out
for the third and last bloody time, i do NOT use fractions in that scenario
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