# Conversion Question

Discussion in 'Homework Help' started by ElectronicsFanatic, May 6, 2012.

1. ### ElectronicsFanatic Thread Starter Member

Feb 12, 2012
30
1
For some reason I have really confused myself on how to do these homework assignments that are asking me to complete the conversions.

Here is one:
0.0001 MHz = ______Hz
What is throwing me off is that it is saying .0001Mkz. I am thinking that i would need to reduce this number to make it smaller since Hz is smaller than MHz so I am coming up with this number:
.1 x 10^-9

Am I doing this right? I don't get the feeling that I am doing this right? Could you send some hints my way?

2. ### bertus Administrator

Apr 5, 2008
18,505
3,568
ElectronicsFanatic likes this.
3. ### ElectronicsFanatic Thread Starter Member

Feb 12, 2012
30
1
Ok I have looked at the metric system prefixes and what is confusing me so much is the fact that it says 0.0001Mhz. I haven't had to deal with decimals like this before. When it says Mhz I think 1,000,000. But the way that my brain is telling me is that this is supposed to be 100μHz but it is in Mhz with μHz notation.

So if i follow the chart you provided i would need to get rid of 6 decimal places to make it 100Hz?

4. ### bertus Administrator

Apr 5, 2008
18,505
3,568
Hello,

Yes, 100 Hz is the correct answer.

Bertus

5. ### ElectronicsFanatic Thread Starter Member

Feb 12, 2012
30
1
Ok, Thanks for the help. I know this is pretty easy, but I got myself all mixed up somehow and needed a push in the right direction again.

6. ### MrChips Moderator

Oct 2, 2009
16,892
5,202
Use $1M = 10^6$

$0.0001 = 10^{-4}$

Hence $0.0001M = 10^{(-4 + 6)} = 10^2 = 100$

Last edited: May 6, 2012
7. ### WBahn Moderator

Mar 31, 2012
22,990
6,884
Here is one place where using the units can really help out. Here is one way to approach it:

$
x Hz = 0.0001 MHz
$

Your goal is to find the value of 'x' that makes this expression true and you will accomplish by multiplying the right hand side by values of 1 (so the value is not changed) but choosing how you express the value of 1 such that the units do change.

$
x Hz = 0.0001 MHz \ \times \ \frac{10^6 Hz}{1MHz}
$

Here we have just multiplied the right hand side by 1, since the numerator (10^6Hz) is equal to the denominator (1MHz).

$
x Hz = (0.0001)(10^6) Hz \ \times \ \frac{1MHz}{1MHz}
$

Here we have just rearranged factors, nothing more.

$
x Hz = 100 Hz
$

Here we have merely carried out the math and removed factors that cancel.

Another way to approach it is to treat the prefix as what it is, a multiplier separate from what it is multiplying:

$
x Hz = 0.0001 MHz
x Hz = (0.0001)(M)(Hz)
x Hz = (0.0001)(M)(Hz) \times \frac{10^6}{M}
x Hz = \frac{(0.0001)(M)(Hz)(10^6)}{M}
x Hz = (0.0001)(10^6)(Hz)
x Hz = 100 Hz
$