In science we encounter problem solving where Conversion of units are needed.  In conversion of units the easiest way is to use dimensional analysis or factor label method, a method of converting one unit to another unit provided the same quantities are involved.   It is a simple technique that needs a little of memorization of the conversion factors to use in calculation.  Dimensional analysis is based on the relationship between different units that express the same physical quantity either metric to metric conversion, metric to English and English to English conversion.

Let us have an example, dollar is different from that of peso but both are amount of money.  One US dollar is equivalent now to 49.72 in Philippine peso.  What if you have 200 US dollar, what is its value in peso?

First thing to do is to have a conversion factor between dollar and peso,  

since the problem is asking the value in mL, mL must be the numerator and L is the denominator, this is for us to cancel out L unit in the calculation as shown below:

In dimensional analysis, we make it sure that the all undesired units are canceled out remaining only the desired unit.

If the desired unit is not obtained in the calculation, meaning something wrong with the calculation and it needs to be reviewed to locate the error.


PRACTICE EXERCISE:

Convert the following:
1.  25.5 mg to g
2.  4.0 x 10^-10 m to nm
3.  0.575 mm to µm
4.  1.48 x 10² kg to g
5.  7.25 x 10^-4 s to ms