# Unit 0, Session 0.4 Useful Calculator Functions

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Unit 0, Session 0.4 Useful Calculator Functions
J. Jackson Barnette, PhD Professor of Biostatistics

Calculator for Course You probably don’t need to buy a calculator for this course; you are probably carrying the best (and cheapest) calculator you can get as: There are hundreds of apps, mostly free, that will do everything you need to do in this class and more Unit 0, Session 0.1 Copyright 2013 JJ Barnette

Session 0.4 Calculator Functions
0.4 Useful Calculator Functions Introductory Biostatistics Session 0.4 Calculator Functions There are many types of calculators that can be used in this class There are some that do many of the complex computations with a few keystrokes I will illustrate some of these using one of my hand calculators, a CASIO fx-115MS Keys vary by calculators so yours may be different, but should have the same operations that can be done Unit 0, Session 0.4 Copyright 2013, JJBarnette

0.4 Useful Calculator Functions
Introductory Biostatistics SQUARE-ROOT Finding a Square-root. The order of the key strokes is important and will vary. To find the square-root of a given number, press the square-root key, then enter the number on the keypad, and press the equal sign. Unit 0, Session 0.4 Copyright 2013, JJBarnette

0.4 Useful Calculator Functions
Introductory Biostatistics SQUARE-ROOT To find the square-root of a value that has been calculated using other operations, press the square-root key, then press the Answer key, and then press the equal sign. This will find the square-root of the previous answer. Unit 0, Session 0.4 Copyright 2013, JJBarnette

0.4 Useful Calculator Functions
Introductory Biostatistics FACTORIAL To find a factorial X!, enter the number X, press the SHIFT key, then the factorial key, then the = sign key. Unit 0, Session 0.4 Copyright 2013, JJBarnette

0.4 Useful Calculator Functions
NATURAL LOG To find the natural logarithm of a number, press the ln key, then enter the number, then the = sign key. If you want the natural log of a computed answer, press ln, then Ans, then the = sign. 0.4 Useful Calculator Functions Introductory Biostatistics Unit 0, Session 0.4 Copyright 2013, JJBarnette

0.4 Useful Calculator Functions
Introductory Biostatistics MULTIPLYING BY e To multiply a number by the constant e ( ), press the ALPHA key, then the e key, then the multiplication key (X), enter the number to be multiplied, and then press the = key. Unit 0, Session 0.4 Copyright 2013, JJBarnette

0.4 Useful Calculator Functions
Introductory Biostatistics FINDING e TO A POWER, ex Used to convert a natural log back to an original scaled value. Press the SHIFT key, press the ex key, enter x on the keypad (the exponent, include – sign if negative), then press = key. Unit 0, Session 0.4 Copyright 2013, JJBarnette

0.4 Useful Calculator Functions
Introductory Biostatistics TAKING A VALUE TO A POWER, Xy Many calculators have this key. If so, enter X, then press the key, then enter y (the exponent), then =. On mine, enter X on the keypad, press the ^ key, then enter y (the exponent), and then press =. Unit 0, Session 0.4 Copyright 2013, JJBarnette

Combinations and Permutations
0.4 Useful Calculator Functions Combinations and Permutations Introductory Biostatistics When we study the topic of probability, we will use two types of counting procedures One is the number of combinations of r items taken from n different possible items (see 0.2, 8), The other is the number of unique sequences of r items taken from n possible items. These are Permutations (see 0.2, 9), These are very time-consuming to compute from scratch, many calculators do these automatically Unit 0, Session 0.4 Copyright 2013, JJBarnette

Combination Key Order: Enter n first, press key, enter r next, press = sign Unit 0, Session 0.4

0.4 Useful Calculator Functions
Introductory Biostatistics COMBINATIONS, nCr Combinations are the number of unique combinations of r items taken from a group of n different items. Here’s the key (SHIFT) on my calculator that finds this. Enter n on the keypad, press the nCr key, enter r and then the = key. Unit 0, Session 0.4 Copyright 2013, JJBarnette

0.4 Useful Calculator Functions
Introductory Biostatistics COMBINATIONS, nCr Combinations are the number of unique combinations of r items taken from a group of n different items. Here’s the key (SHIFT) on my calculator that finds this. Enter n on the keypad, press the nCr key, enter r and then the = key. Unit 0, Session 0.4 Copyright 2013, JJBarnette

Permutation Key Order: Enter n first, press key, enter r next, press = sign Unit 0, Session 0.4

0.4 Useful Calculator Functions
Introductory Biostatistics PERMUTATION, nPr Permutations are the number of unique sequences of r items taken from a group of n items. Here’s the key (SHIFT) on my calculator that finds this. Enter n on the keypad, press the nPr key, enter r and then the = key. Unit 0, Session 0.4 Copyright 2013, JJBarnette

0.4 Useful Calculator Functions
Introductory Biostatistics PERMUTATION, nPr Permutations are the number of unique sequences of r items taken from a group of n items. Here’s the key (SHIFT) on my calculator that finds this. Enter n on the keypad, press the nPr key, enter r and then the = key. Unit 0, Session 0.4 Copyright 2013, JJBarnette

Conclusion This is the final session in Unit 0 It is intended as a review of basic mathematics used in biostatistics with a focus on how these will be used in this course If there are mistakes found of other topics that you feel should be included, please contact Dr. Barnette Unit 0, Session 0.4

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