2. The Metric System Ms. Ryan MCATC Medical Math 2015-2016

3. Basic Units of Metric Measurement 2

4. Understanding Metric Notation  Metric system is based on multiples of 10.  Prefix before the basic unit indicates size.  Kilo – indicates you multiply the basic unit by 1000.  Kilometer – 1000 meters  Kilogram – 1000 grams  Kiloliter – 1000 liters 3

5. Understanding Metric Notation  Prefix milli- means one-thousandth.  Millimeter is one-thousandth of a meter.  Milliliter is one-thousandth of a liter.  Milligram is one-thousandth of a gram. Chapter 3 4

7. Convert Larger to Smaller  2 L = ?? mL  mL = 0.001  Move the decimal to the right 3 places  2.0 L = 2000 mL  OR multiply  2 X 1000 = 2000

8. Convert Smaller to Larger  250 mg = ?? g  milli = 0.001 so move the decimal point 3 places to the left  250 mg = 0.250 g (drop the trailing zero)  OR divide 250 ÷ 1000 = 0.250

9. Metric System RULES  Do not use a period with the abbreviation of metric units  May be mistaken for another letter or symbol  Correct: 1) mg 2) ml  Incorrect: 1) mg. 2) ml.

10. Metric System RULES  Use Arabic numerals to express the quantity of the dose  Correct: 4 mg  Incorrect: IV mg

11. Metric System RULES  Meter and gram are abbreviated with lowercase letters.  Liter is abbreviated with an uppercase L.  This minimizes the chance of confusion between 1 and the lowercase l. 10

12. Metric System RULES  Write fractions as decimals  Example: Write 1.25 g to represent 1 1/4 g  If the quantity is less than 1, include a 0 before the decimal point.  Example: Do not write.750 write 0.75  No trailing zeros: 0.750 is written as 0.75 11

13. Metric System RULES Write the unit after the quantity with a space between them.  Example: Write 30 mg not mg 30 12

14. Example for Practice  Consider the previous rules to determine the correct metric notation for six and two-eighths milliliters. a. 6.28mL b. ml 6.25 c. 6 mL d. 6.25 mL Chapter 3 13 Answer d. 6.25 mL

15. REMEMBER Converting within the Metric System To convert a quantity from one unit of metric measurement to another: 1. Move the decimal point to the right if you are converting from a larger unit to a smaller unit. 2. Move the decimal point to the left if you are converting from a smaller unit to a larger unit. 14

16. Examples for Practice 1. Convert 4 L to mL. 15 2. How many m are in 75 mm?

17. Error Alert!  Remember: The larger the unit, the smaller the quantity. The smaller the unit, the larger the quantity.  Example : 1 dollar bill = 4 quarters = 100 pennies  Example : 100 pennies = 4 quarters = 1 dollar bill 16