CALCULATIONS CHAPTER 6

ROMAN NUMERALS

Positional notation – When the second of two letters has a value equal to or smaller than that of the first, add their values ixvi = = 66 – When the second of two letters has a value greater than that of the first, subtract the smaller from the larger xc = 10 subtracted from 100

SIGNIFICANT FIGURES Four rules for assigning significant figures: 1. Digits other than zero are always significant. 2. Final zeros after a decimal point are always significant. 3. Zeros between two other significant digits are always significant. 4. Zeros used only to space the decimal are never significant.

METRIC SYSTEM LIQUIDS

METRIC SYSTEM SOLIDS

AVOIRDUPOIS SYSTEM

APOTHECARY SYSTEM

HOUSEHOLD UNITS

TEMPERATURE 9C = 5F For example, to convert 37C to Fahrenheit: 9(37) = 5(F) – = 5F – = 5F 98.6 = F For example, to convert 98.6F to Celsius: 9C = 5(98.6) – 160 9C = 493 – 160 9C = 333 C = 37

RATIO & PROPORTION A ratio states a relationship between two quantities Two equal ratios form a proportion Rules for using ratios and proportions 1.3 of the 4 values must be known 2.Numerators (values in front of colons) must have same units 3.Denominators (values behind colons) must have same units

Examples You receive a prescription for KTabs one tablet bid x 30 days. How many tablets are needed to fill this prescription? 1.Define the variable and correct rations: Unknown variable (X) is the total tablets needed Known ratio is 2 tablets per day Unknown ratio is how many tables are needed for 30 days 2. Set up the proportion equation: X tabs : 30 days = 2 tabs : 1 day 3. Solve: X = 60 tabs

Examples If an antidiarrheal mixture contains 3ml of paregoric in each 30ml of mixture, how many ml of paregoric would be contained in a tsp of mixture? (note 1 tsp = 5ml) 3ml paregoric : 30ml mixture = xml paregoric : 5ml mixture 15ml = 30x 0.5ml = x

Complete page : Answers: 1.2ml 2.8ml 3.75ml ml/mn ml

Percents & Solutions Percents are used to indicate the amount, or concentration, of something in a solution. Weight-to-Volume: grams per 100 milliliters g/100ml Volume-to-Volume: milliliters per 100 milliliters ml/100ml

PERCENTS & SOLUTIONS Percent Weight-to-Volume – Grams per 100 milliliters Percent Volume-to-Volume – Milliliters per 100 milliliters Milliequivalents – mEq

Percents / Solutions Examples If there is 50% dextrose in a 1,000 ml IV bag, how many grams of dextrose are there in the bag? 1. Proportion equation: Since 50% dextrose means there are 50 grams of dextrose in 100 ml, the equation would be: xg / 1,000ml = 50g / 100ml 2. The x equation: xg = 1,000ml x 50g/100ml = 10 x 50g = 500g Answer = There are 500g of dextrose in the bag

Example Now how many ml will give you a 10g of dextrose solution? 1. The proportion equation: xml: 10g = 100ml: 500g 2. The x equation: 500xml/g = 1000ml/g X = 20ml

Complete page (click for answers) 1.60% 2.80% 3.12% g g 9.14g 10.50ml 11.70ml 12.20ml %

ALLIGATION

POWDER VOLUME FV = D + PV

CHILDREN’S DOSES Clark’s Rule Young’s Rule Body Surface Area Body Weight

CALCULATIONS FOR BUSINESS