# why can't i grasp metrics?

Discussion in 'Et Cetera, Et Cetera' started by surferboy, Jan 18, 2009.

1. ### surferboy Gold Member

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i know the conversions. but i can't convert metrics to metrics. like, i know an inch is 2.54cm. my quiz question was "what is one inch in mm?" i put .254

dammit

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2. ### pym New Member

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25.4mm

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Last edited: Jan 18, 2009
3. ### B_mitchymo New Member

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leave it out.....its math!

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4. ### exwhyzee Gold Member

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I do wish the US would switch over to metrics...along with the rest of the world.

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5. ### surferboy Gold Member

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instead of telling me to multiply or divide, i wish they would have told me which way to move the decimal

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6. ### Mem Gold Member

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It's decimal points that you can't grasp.

A centimeter is 1/100 of a meter. A Millimeter is 1/1000 of a meter.

It's 10 times smaller. 2.54 times 10 = 25.4 mm. You divided by 10 instead, or put the decimal point in the wrong place.

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7. ### surferboy Gold Member

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8. ### HazelGod Gold Member

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The easiest way to learn is to draw it out in dimensional analysis every time until you grasp it intuitively. That way, you see exactly how the units line up (insert sophomoric sniggering here) each time.

For example:

Code:
``` 2.54 cm     10 mm       25.4 mm
--------- x  -------  =  --------
inch         cm          inch```

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Last edited: Jan 18, 2009
9. ### Principessa Gold Member

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Sorry you missed a question on your quiz. :frown1:

Short Answer: Because you're American! Other than sodas and other beverages the only place I can think of where the metric system is commonly used is for tools for automotive repair.

Long Answer: There isn't much focus on metrics in elementary school. If a teacher spends two weeks on the metric system that is a lot. By the time one gets to middle school or high school the focus is on college preparatory mathematics such as algebra, geometry, calculus, probability & statistics, and trigonometry.

Frankly, I'm surprised you had a quiz on the metric system in college. Are you an engineering major? Sometimes wiring and machine parts are done in metrics.

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10. ### jason_els <img border="0" src="/images/badges/gold_member.gi

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Metric is a silly system invented by the French. The American system is far more colorful and occasionally more accurate. Viva cultural differences!

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11. ### D_Ivana Dickenside New Member

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you're not alone. i don't understand metrics either... and neither did my algebra class last semester. the professor tried teaching the metric system and everyone failed his exam on conversions. that's 50 other people in california, along with me and you, who don't get it and probably never will.

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12. ### Principessa Gold Member

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The metric system is as relevant to life in the USA as the horse and buggy or the Edsel.

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13. ### pym New Member

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If you plan to make your living as a Chemist,physicist,applied science's, Engineer,mechanic,pharmacist,Machinist,Assembler,appliance repair,quality assurance,manufacturing..... and quite a few others.......
You'll need to understand the metric system.
ALL modern applications center and reference to the metric system.

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14. ### Gl3nn Gold Member

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I don't understand why they don't use cm, meters, ....

It's just: one, ten, hundered, thousand, .....

The same with kilograms, ... instead of ounces, etc.

How much easier can it be?

Sorry to hear you got it wrong on your quiz

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15. ### vince Gold Member

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The metric system is soooo easy. It's when you start converting to and from the old Imperial (American) system, that you run into trouble.

10 mm = 1cm
100cm = 1 meter
1000m = 1 kilometer

You know that 1 inch = 2.54cm. Right?
So to get mm, multiply the cm by 10...
2.54 x 10= 25.4 ...
All you have to do is move the decimal point one place to the right every time you change a measurement from cm to mm.

Metric is based on nature.
1 kilogram is the weight of 1 liter of water.
For volume, 1 cubic liter is the space occupied by 1 liter of water.
There are 1000 cc's (cubic centimeters) in a liter.
Therefore 1cc of H2O weighs 1 gram. 1000 grams = 1 kilo.

I was phobic about the metric system too until I moved back to Canada and was forced to use it. Even there, because they didn't change to metric until the 60's many things are still measured in inches and pounds.

Now I live in a totally metric place and I guess I'm bilingual.

As pym pointed out, it is relevant to life in America. I think surferboy is going into the medical field isn't he? It is totally used there.

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Last edited: Jan 19, 2009
16. ### chrwl007 VerifiedGold Member

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Sounds like the opposite of this side of the Atlantic. I'm absolutely clueless when it comes to imperial units. All I know is that 12in. = 1ft. and 1mi. = 1.6km. Then again, I'm in science, so I'm glad that I know my metric system inside-out.

M(ega)
K(ilo)
unit
m(illi)
micro
n(ano)
p(ico)
f(emto)

For every unit you go down, it's x10^3 (x1000). So 1 unit (say litres) would be 100 000 microlitres. To go up, divide by 1000 (1 litre = 1x10^-6 Megalitre). Centimeter is the only exception. It is 100th of a meter, and 10x millimeter (hit me over the head if that didn't make sense :redface

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17. ### tullcitytom New Member

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I find it difficult to think in terms of metrics. I never had a problem with metric tools or fractional inch tools. But lengths needed to be in inches, fractions or decimals- it didn't matter. Metrics on the other hand was different. I always had to convert it to inches. One of our leads at work used to say that the U.S. was going to convert to the metric system and I would always argue that it wouldn't. Much of the U.S. infrastructure is built on inches. The building trade isn't going to convert. Boeing definitely is not going to convert. All their drawings are in inches and every part of a plane has its own drawing. The education system using the metric system seems to work. I can't imagine Chemistry classes using ounces and pints, or even cubic inches to teach the students. Metrics has its place. I remember when the Canadian radio stations used to talk about converting . Not living there I never did find out to what extent they converted. Does anyone know if they still use inches when building houses?

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18. ### arthurdent Gold Member

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The metric system is in base 10, so it's much easier to do arithmetic with. Whereas, the imperial system is in base 12, which makes it much more difficult.

For example, say you have 10 identical Christmas gifts which you want to tie-up with ribbon and you know it takes 8ft 4in of ribbon to tie-up one (they're big presents), so how much ribbon do you need to tie-up 10 gifts?

8ft = 96in
8ft 4in = 100in
1000in / 12in = 83ft with some left over
83ft x 12in = 996in
1000in - 996in = 4in
So it would take 83ft 4in of ribbon to tie-up the 10 gifts.

or

8ft 4in x 10gifts = 80ft 40in
40in / 12in = 3ft 4in
80ft + 3ft 4in = 83ft 4in

whereas if you start with the ribbon in metric first (1in = 2.54cm, so 100in = 254cm)

254cm x 10gifts = 2540cm = 25.40m (ie. 25m 40cm) of ribbon to tie-up 10 gifts.

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19. ### mindseye Gold Member

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Other people have thoroughly explained the metric system, how to convert units, and how decimals work.

Instead, let me suggest that you rely on your common sense about everyday objects. You said you knew that an inch is 2.54 cm. Since a millimeter is smaller than a centimeter, do you need more of them, or less of them to make an inch?

If you can answer that question, then you know which way to move the decimal point without having to know anything 'mathy'.

So, how far should you move it? Is the answer 25.4mm, 254mm, or something even bigger? What objects do you know that are measured in millimeters? 35mm film? A 9mm bullet? If you're familiar with the sizes of these objects, then you probably can deduce the right answer: 35mm film is pretty close to an inch wide, so 25.4mm makes more sense than 254mm.

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20. ### vince Gold Member

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For rough and ready converting back and forth some of the conventions I use-
These are NOT exactly, Just kinda close.

2.5 cm (25mm) = 1 inch
10cm = 4 in
30cm = 1 foot
40cm = 16 inches and so on...

100 km = 60 miles

250ml = 1 cup

when all else fails- >:: World Wide Metric ::<

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