Decimals v. Fractions

[Tex]

Hey there, fellow Kerbonauts.

I was wandering around the forums, bored, and I was thinking about different sizes of rockets. Thinking about 2.5m rockets eventually got me thinking about decimals. I always prefer to not only do my calculations using them instead of fractions, but also I try to convert fractions to decimals whenever I can.

Personally, I prefer working in decimals for simplicity and ease of operation, but what' y'all's take on it?

[Klingon Admiral]

As someone who studied math for one semester, I HAVE to go with fractions. Decimals suck.

[Ralathon]

Depends on what I'm doing. If I'm dragged away from my precious calculator and I actually have to do stuff by head I vastly prefer fractions.

63/23 * 54/13 = (63*54)/(23*13) = 3402/299 is a lot easier than trying to figure out that 2.73913043478 * 4.15384615385 = 11.3779264214

However, I'm a physicist IRL and I find the decimal notation much more intuitive. If my calculations say the flowrate is 1.3058 cm^3/s I can see much faster if that's within my expectations (And thus whether I'm botching the calcs) than when I end up with 47261/36193 cm^3/s.

So in the modern world where computers do the grunt work I prefer decimal but if I find myself in the middle of nowhere without batteries or power I'll resort to fractions.

[Banbite]

Fractions are also more accurate, they don't have the same amount of floating point rounding errors as decimals do, I think. But both has their uses, decimals are easier to read but fractions are easier generally better to do math with. And also stuff like 1/3 vs 0.3333333... etc.

[Nuke]

its easier to implement functions in code with decimals, since fractions are easy to convert to decimal with reasonable precision. if you are working on low level embedded platforms like where you need to use ints or dont have a floating point unit to work with and need to implement fixed point maths. you just pick a bit to be the ones place and the bit to the right of it is the 1/2 place, followed by the 1/4 place and so on. add and subtract work as normal, multiplies and divides require shifts. some other cases where you need to use fractions is if you have a hardware multiply but no divide (points at atmel). since division by a number is equivalent to multiplication by its reciprocal, you usually use reciprocal constants just to make things faster. so at least in programming you kinda need to be familiar with both ways to get anywhere.

[Arbolus]

I always find it far simpler and more useful to do all the calculations in fractions and only convert it to decimals once I've found the answer. If I'm trying to solve something like mε = p²/2m + J²/2mr² - GMm/r I always prefer to see what cancels or simplifies and thereby saves me the effort of writing it out, and I never actually introduce any numbers until I've got a symbolic expression for the solution.

Sometimes it can be slightly easier to use decimals. When coding I might type a*b*0.45*c*d rather than a*b*(1/5 + 1/4)*c*d just because it saves me a few characters, but I'd never do anything like that on paper.

[Drunkrobot]

"Fractions are beautiful."-A genuine quote from my GCSE Maths teacher.

To answer the question, both have their ups and downs. When I'm doing Maths, I tend to use fractions, Ralathon above explained how much more intuitive fractions are in multiplication. In the more concrete worlds of Physics and Chemistry, I usually opt for decimal. However, to second my Maths teacher, when I have a choice of giving an answer in decimal or fractions, I go for the more elegant fractions.

-An AS-level student. (Physics, Chemistry, Biology and Maths.)

[DaveofDefeat]

I hate decimals because I hate infinity with a passion.

[softweir]

I hate decimals because I hate infinity with a passion.

In that case, might I present you with the fraction 1/0.

Sorry, that old infinity catches up with you no matter how fast you run!

*grin*

[Aghanim]

Until I found out how to calculate parallel resistance using decimal, I'm using both of them right now

[Brotoro]

Fractions are the rational choice.

[cantorobriar]

I'd have to say fractions, beacuse you can have decimals IN fractions Like this --> 2.5

---

10 (Which obviously equals 1 over four, it was just for demonstration purposes.)

There are many other reasons, too. It's alot easier to write proportions with fractions instead of decimals, and even more things. The only advantage I see that decimals have is that it's easy to convert to a percent.

[DaveofDefeat]

Also, decimals means................SIG FIGS BUM BUM BUMMMMMMMMMMMMMMMMMM

I hate significant figures almost as much as I hate infinity.

[jwenting]

either/both depending on what you're using them for. This whole "which is better" meme is ridiculous.

[rpayne88]

I don't for reasons said above. Don't get me started on radicals and algebraic expressions, though.

[Seret]

This is a bit like asking: which is better, a hammer or a screwdriver? They're different tools, they do different jobs. You need to have both in your tool box.

[sjwt]

My take...

Fractions are imaginary numbers, and need to be treated as such.

[Idobox]

In my engineering school, and I guess in pretty much any serious scientific context, we had to do our math in symbolic form and at the end put values and get a result, usually as a decimal.

Decimals are easy to read but introduce an error, fractions are exact but can be abstruse.

For engineering purposes, decimals are usually good enough to represent values, but you should try to avoid them in calculations as much as you can.

[SpaceSphereOfDeath]

Depends on the base.

In bi/trianry, fractions are appalling:

1001

1010 Or in decimals: 0.0101

However in higher number bases (base ten/12/16)

Fractions make more sense

[Eric S]

Depends on what I'm doing with them. Fractions are pretty common for me as intermediate steps or if variables are involved. On the other hand, if it boils down to a number with a fixed meaning, tables are much easier to sort and compare results using decimal notation.

[Yourself]

My take...

Fractions are imaginary numbers, and need to be treated as such.

Well, they're rational numbers.

[Seret]

For engineering purposes, decimals are usually good enough to represent values, but you should try to avoid them in calculations as much as you can.

I'm an engineer. I'd say decimals are fine in calculations as long as you take care to use full precision at every step, and only round your result. Rounding too early is a major source of errors.

[drakesdoom]

I work on the other end, metal fabrication and production. The shop I am in does not do terribly precise work, understand that precision is expensive in production and is avoided if possible. Now even this not very precise work has total tolerances as low as 0.0016 inches, we may have tighter but that is the most I have seen. Once we get into actually cutting the part we measure in decimal, but before that all stock, parts, bolts, screws, machines, chucks, collets , taps, drills, and dies are in fractions.

[Seret]

Fractions are a bit more common in Imperial work though, because an inch is an inconveniently large unit for most things so has always been chopped up into fractional units. If you were using metric you'd be doing it all in decimal.

[drakesdoom]

Yes but then I would have to call my bullets something silly like 12.5mm instead of .50 cal, or even worse that horrid squib round called 9x19mm instead of a good proper hole maker like .45 cal.