PHARMACEUTICAL MATH I PHRA 1209

The metric system was developed in 19th century France. The United States is one of the few countries not using the metric system.

The metric system has three basic units for measuring matter:

• gram  (mass)
• liter (volume)
• meter (distance)

The units are expressed in multiples of 10.

The metric system uses prefixes to define multiples or fractures of the basic units.

Conversion of metric to metric

Metric conversions uses dimensional analysis (factoring) to convert one metric prefix to another.   The conversions is accomplished by conversion factors:

Example: Convert 4 grams to mg.

 

Example: Convert 80 ml to kl.

You have two sets of conversion factors.

or

or

Since we do not know how to convert directly from ml to kl, we first convert ml to liters then liters to kiloliters.

Example: Convert 5 cm to um

You have two sets of conversion factors:

You have two sets of conversion factors:

You have two sets of conversion factors:

or

or

Since we do not know how to directly convert from cm to um, we first convert to liters than to um.

Metric - English Conversions

Sometimes it is necessary to convert from the english system to the metric system or vice versa.

To do this we need three conversion factors.

1 in  = 2.54 cm

1 lb  = 454 g

1 qt  = 946 ml

Example: Convert 24 oz. to kg

Example: Convert 8 meters to yards.