converting mm to cm and dm to mm

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converting mm to cm and dm to mm

Postby headway78 » Wed Sep 15, 2004 7:16 am


Re: converting mm to cm and dm to mm

Postby Knight » Sat Sep 18, 2004 1:55 am

headway78 wrote::cry:

Just taking a guess here... The :cry: translates to "I don't get it!"

Step one: Relax. This is easy stuff.

You are talking about various measurements of length, all based on the meter. The magic of the metric system. Look at your hands. Unless you've had an accident or a birth defect, you've got ten fingers. That's all you need to handle the metric system. EVERYTHING is done in units of ten. No more worrying about 12 inches to a foot, and three feet to a yard, and so forth. We've got one unit, and we multiply and divide it by factors of ten to make it fit what we want.

Your first problem: mm to cm.

mm means millimeters. A millimeter is 1/1000 of a meter. cm mens centimeters. a centimeter is 1/100 of a meter. Notice that a mm is a factor of ten smaller than a cm? That means that a cm is a factor of ten bigger... So, if you've got 10 mm, that means you have 1 cm. 100 mm? thats 10 cm.

Now for dm to mm. We already know that a mm is 1/1000 of a meter. dm means decimeter. Thats 1/10th of a meter. Hmm. a decimeter is 100 times bigger than a mm. a mm is 100 times smaller than a dm. So... 1 dm = 100 mm. 10 dm = 1000 mm (which incidentally is one meter!).

OK... Now your probably asking where to find out what all the prefixes are... Most of the "bigger than" ones you already know from computers. Kilo. thats a 1,000. Mega. that a million; 1,000,000. Giga. That'd be a thousand million.... 1,000,000,000. Next is Tera. 1,000,000,000,000. Much beyond that we don't use often. There are a few that are used less frequently, like deka (da), for 10, and hecto (h) for 100.

Now for the small ones. deci, centi, and milli you've already met. that'd be 1/10th, 1/100th, and 1/1000th. Next comes micro, or 1/1,000,000 which uses the symbol µ, then nano, 1/1,000,000,000 which uses a lower case n, and then pico 1/1,000,000,000,000 which uses a lower case p. You won't generally use numbers much smaller than this either.

So, a chart:

Code: Select all
Tera (T) = 1.0e+12 or 1,000,000,000,000
Giga (G) = 1.0e+09 or 1,000,000,000
Mega (M) = 1.0e+06 or 1,000,000
kilo (k) = 1.0e+03 or 1,000
hecto (h) = 1.0e+02 or 100
deka (da) = 1.0e+01 or 10
deci (d) = 1.0e-01 or 0.1
centi (c) = 1.0e-02 or 0.01
milli (m) = 1.0e-03 or 0.001
micro (µ) = 1.0e-06 or 0.000,001
nano (n) = 1.0e-09 or 0.000,000,001
pico (p) = 1.0e-12 or 0.000,000,000,001

In reality, converting metric units is merely a matter of moving the decimal point!

one cm. To convert this to mm move the decimal point one to the right, because your making it 10 times bigger. so 1 cm is 10 mm.
William J. Knight
Health Physicist
Los Alamos National Labs
User avatar
Posts: 309
Joined: Tue Jan 13, 2004 9:43 pm
Location: Los Alamos, NM

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