# Help understanding metric units

1. Nov 29, 2013

### tomtomtom1

Hi all

Firstly this is not a homework question. I just found myself wondering what certain numbers meant while at work and realised that i didnt actually know hence the posting.

I was hoping someone could help explain & confirm a couple of things about units.

1) Given the number 4.172 meters
I interpret this number at 4 whole meters
And the 0.172 part I interpret as a portion of a whole meter
My first question is this; is 0.172 (the fractional part) still in meters or is this in cm?

2) Assuming that 0.172 is in meter then to understand the 0.172m a little better I have done the following:-

1 ● 1 / 10 1 / 100 1 / 1000
0 ● 1 7 2

I have re-writtern this fractional part as 172/1000

My understanding at this point is that the denomniator (1000) represents my whole meter and the numerator represents the portion of the whole meter
Is this correct?

Attached is a PDF document where i have tried to understand more about units which i was hoping someone could look at.

#### Attached Files:

• ###### Unit question.pdf
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2. Nov 29, 2013

### Staff: Mentor

If I give you 1/2=0.5 apples, I give you 1/2 of an apple and not 1/2 of [something else].
If I give you 3.5 apples, I give you 3 apples and 1/2 apple and not 3 apples and 1/2 of [something else].

It is correct, and you can get the same just with rewriting the numeric value:
3.172 meters = (3172/1000) meters = (3 + $\frac{172}{1000}$) meters