Unit Conversions

0 Unit Conversions By Tim Fahlberg Tim.Fahlberg@gmail.com Please feel free to email me!

0 Objectives • Convert units within the metric system. • Convert units between the metric and apothecary system. A-2

How confident do you feel about using the metric system? • Very confident • Somewhat confident • Not very confident • What’s the metric system?

How confident do you feel about your math skills (i.e. algebra)? • Very confident • Somewhat confident • Not very confident • I have no confidence about being able to do math

Do you enjoy math? • Yes, math is great! • Yeah, I like math pretty well • I’m ambivalent about math • I don’t like math • I hate math

0 The metric system • Quick check/test:

0 The metric system is a decimal system based on • Multiples of 10 • Fractions of 10 A-2

0 What are the basic units of measurement in the metric system? • Grams • Liters • Meters A-3

0 What do these units measure? • Grams • Unit for weight • Liters • Unit for volume or capacity • Meters • Unit for length A-6

0 What are 4 different ways to write grams? • g • gm • G • Gm A-4

0 What are 2 different ways to write liters? • l • L A-2

0 What are 2 different ways to write meters? • m • M A-2

0 Metric prefixes commonly used in medicine • Larger units • kilo (k) - kg • Smaller units • centi (c) – cm (think hundredth – like cents in a dollar) • milli (m) – mm, ml, mg (think thousandth) • micro (mc) – mcg (think millionth)

0 Weight per gram • 1 kilogram (kg) = ____ g • 1000 • 1 gram (g) = 1 g • 1 milligram (mg) = ____ g • .001 (again – think thousandth) • 1 microgram (mcg) = ____ g • .000001 (again – think millionth)

0 Volume per liter • 1 liter (l) = 1 liter • 1 milliliter (ml) = ___ liter • .001

0 Length per meter • 1 kilometer (km) = _____ meters • 1000 • 1 meter (m) = 1 meter • 1 centimeter (cm) = ____ meter • .01 • 1 millimeter (mm) = ____ meter • .001

0 Metric units review (Length) • 1 m = ____ cm • 1 m = 100 cm • 1 cm = ____ m • 1 cm = .01 m

0 Metric units review (Length) • 1 m = ____ mm • 1 m = 1000 mm • 1 mm = ____ m • 1mm = .01 m

0 Metric units review (Weight) • 1 kg = ____ g • 1 kg = 1000 g • 1 g = ____ kg • 1 g = .001 kg

0 Metric units review (Weight) • 1 g = ____ mg • 1 g = 1000 mg • 1 mg = ____ g • 1 mg = .001 g

0 Metric units review (Weight) • 1 g = ____ mcg • 1 g = 1,000,000 mg • 1 mcg = ____ g • 1 mcg = .000001 g

Metric units review (Volume) • 1 l = ____ ml • 1 l = 1,000 ml • 1 ml = ____ l • 1 ml = .001 l

Conversion within the Metric System • Why is this important? • Drug administration often requires conversion within the metric system to prepare the correct dosage.

0 Conversion within the Metric System Two methods: • Changing from a larger unit to a smaller unit. • For example, “Change 1 g to mg.” • Changing from a smaller unit to a larger unit. • For example, “Change 120 ml to l.”

0 Conversion within the Metric System To change from a larger unit to a smaller unit: • Multiply by the correct power of 10 or use the conversion factor.

0 Problem 1: • Convert 2.5 liters (l) to milliliters (ml) • Ask: “Which is bigger, 1 L or 1 ml?” • So, are there a bunch of liters in a ml or a bunch of ml in a liter? And how many? • Should the answer be more or less than 2.5? • Let’s do the calculation … (Next slide please)

0 Problem 1: (Continued) • Convert 2.5 liters (L) to milliliters (mL) • Ask: “Is this answer reasonable?”

0 Problem 2: • Convert 4.8 grams (g) to milligrams (mg) • Ask: “Which is bigger, g or mg?” • So, are there a bunch of grams in a mg or mg in a gram? How many? • Should the answer be more or less than 4.8? • Let’s do the calculation … (Next slide please)

0 Problem 2: (Continued) • Convert 4.8 grams (g) to milligrams (mg) • Ask: “Is this answer reasonable?”

0 Conversion within the Metric System To change from a smaller unit to a larger unit: • Divide by powers of 10 or use the conversion factor.

Problem 3: • Convert 1300 milliliters (ml) to liters(l) • Ask: “Which is bigger, ml or l?” • So, are there a bunch of milliliters in a liter or liters in a milliliter? How many? • Should the answer be more or less than 1300? • Let’s do the calculation … (Next slide please)

Problem 3: (Continued) • Convert 1300 milliliters (ml) to liters(l) • Ask: “Is this answer reasonable?”

Problem 4: • A patient problem • Joe weighs in at the health clinic and notices that he’s gained 5 kg of weight since yesterday. • How much fluid might he have gained since yesterday?

Problem 5: • The doctor has prescribed 0.15 mg of a drug. How many micrograms is this? • Ask: “Which is bigger, milligrams (mg) or micrograms (mcg)?” • So, are there a bunch of milligrams in a microgram or vice versa? How many? • Should the answer be more or less than 0.15? • Let’s do the calculation … (Next slide please)

0 Problem 5: (Continued) • Convert 0.15 mg to mcg. • Ask: “Is this answer reasonable?”

0 Problem 6: • A wound on a patient is 7.5 mm. How many cm is this? • Ask: “Which is bigger, mm or cm?” • So, are there a bunch of mms in a cm or vice versa? How many? • Should the answer be more or less than 7.5? • Let’s do the calculation … (Next slide please)

0 Problem 6: (Continued) • Change 7.5 mm to cm. • Ask: “Is this answer reasonable?”

0 The Apothecary System • What are the basic units of measurement in the apothecary system that are most useful in nursing? • Weight • Grains (gr) • Liquid volume • Quarts (qt) • Pints (pt) • Fluid ounces (fl oz)

0 The Household System • What are the basic units of measurement in the household system that are most useful in nursing? • Teaspoons (tsp) • Tablespoons (Tbsp) • Ounces (oz) • Cups

Conversion - Apothecary– Metric – Household Systems • How many … ? Weight • ___ milligram(s) (mg) = ___ grain(s) (gr)? • Approximately 60 mg = 1 gr

Conversion - Apothecary– Metric - Household Systems • How many … ? Volume • ___ pint(s) = ___ quart(s) (qt) • 2 pt = 1 qt • ___ fluid ounce(s) (oz) = ___ cc • 1 fl oz = 30 cc

Conversion - Apothecary– Metric – Household Systems • How many … ? Volume (Continued) • ___ Tablespoons = ___ Fl oz = ___ cc • 2 Tbsp = 1 fl oz = 30 cc • ___Tbsp = ___ cc • 1 Tbsp = 15 cc

Conversion - Apothecary– Metric – Household Systems • How many … ? Volume (Continued) • ___ Teaspoons = ___ Tablespoons = ___ cc • 3 tsp = 1 Tbsp = 15 cc • ___ tsp = ___ cc • 1 tsp = 5 cc • ___ cup = ___ oz = ___ cc • 1 c = 8 oz = 240 cc

Unit Conversions