Basic math refresher 2012

Basic Math Refresher


Roman Numerals

I=1 V=5 X=10 C=100 D=500 M=1000

Nursing required competency in mathematical skills in order for you to be able to administer medications to your patients safely. Use the following basic math refresher to build the foundation for developing proficiency in the mathematical skills necessary for nursing.

Roman Numerals - General Rule

The basic form is to place the larger numerals to the left and add other numerals.

Example: XXXIII = 33, which is (XXX = 30) + (III = 3) = 33

Note: If there seems to be several ways of writing a number, use the shorter form.

XXI – 21, which is (XX=20) + (I = 1) = 21, not XVVI (X = 10 + V = 5 + V = 5 + I = 1)


Roman Numerals – Exception

The exception to the basic form is if smaller numerals precedes a larger numeral, the smaller should be subtracted from the larger.

Example: IX = 9(I = 1) - (X = 10) = 1 – 10 (really 10 – 1) = 9

Note: only one smaller numeral can precede a larger numeral.

Example: XCV = ((X = 10) – (C = 100)) + (V = 5) = 95 correct, not IXCV (two smaller numerals preceding the C (100)).

Note: Roman numerals can be written in upper case and lower case.

Examples: IV or iv = 4


Fractions

A fraction is a way of representing division of a 'whole' into 'parts'. It has the form:

Numerator Denominator

where the Numerator is the number of parts chosen and the Denominator is the total number of parts.


FRACTION TYPES

There are 3 different types of fractions:

Proper Fractions: Numerator < Denominator - Proper fractions have the numerator smaller than the denominator. Examples are ½, ⅖, or ⅞.

Improper Fractions: Numerator > Denominator or Numerator = Denominator - Improper fractions have the numerator greater or equal to the denominator. Examples are 5/5 or 7/2.

Mixed Fractions - Mixed fractions have a whole number plus a fraction. Examples are 2 and ⅕ or 123 and ⅞.


1 0.3333--- = 3 ) 1.0000 3 9

10 9 10 9

10 9 10 infinite

Converting a fraction into a decimal - examples

1 ____ 0.25--- = 4 ) 1 = 4 ) 1.00 4 8

20 20 0


Decimals

Decimals and the conversion of decimals to fractions and fractions to decimals is a necessary skill in the nursing profession.

Relative Values of Decimals

Values on the left side of the decimal are increasing in value

100.00 is larger than 10.00

Values on the right side of the decimal are decreasing in value

0.1 is larger than 0.01


Relative Value of Decimals

1 2 3 4 . 5 6 7 8

Thousands

Hundreds

Tens

Ones Tenths

Hundredths

Thousandths

Ten Thousandths


Convert a decimal into a fraction - example

.25 = 25 hundredths (5 is in the hundredths position)

= 25 100 (reduce the fraction)

= 1 4


Rounding RulesRounding Rules

ml or cc Tablets

If the answer is < 1cc (or ml) then round to the nearest 100th.Ex: 0.376 = 0.38 cc (or ml)

If the answer is > 1cc (or ml) then round to the nearest 10th.Ex: 1.57 = 1.6 cc (or ml)

Tablets, as a rule, can only be given whole or broken in half.

Round to the nearest half (0.5)Ex: 1.45 = 1.5 tablets 1.2 = 1 tablet

Round at the end of the problem, when you get to the answer (exception is when you’re converting pounds to kilograms (kg)) then you should round to the nearest tenth as soon as you convert, then complete the problem. (2.345 = 2.4)

Basic Math RefresherRounding Rules

• Rou

Basic Rounding RememberIf the number is 5 then round up. Ex: 1.57 = 1.6 1.45 = 1.5 0.686 = 0.69

If the number is < 5 then round down. Ex: 0.543 = 0.54

Round at the end of the problem.

Converting pounds and kilogramsRound to the nearest 10th.Ex: 120 pounds = 54.54 or 54.5 kg

The exception to this rule is when you are converting pounds to kgs. Always convert and round to the nearest 10th and then complete the problem.

Education

Basic math refresher 2012