Sunday, May 2, 2021

TI-84 Plus CE and Casio fx-CG50: Interest Only Loans

TI-84 Plus CE and Casio fx-CG50:  Interest Only Loans


Interest Only Loan: Is it a Good Idea?


An interest-only loan is a loan where you pay only the interest of a loan, at least for a certain amount of time.  Why would some one want to engage an interest only loan?  The payment for when you are paying just the interest is lower.  However, the principal does not go down during that time, and the principal of the loan is going to have to be paid sometime.


Interest only loans can be helpful for people who expect a large increase of income in the near future or for those who like to flip properties.  Personally, I don't recommend it, when I take a loan, I want to pay off a portion of the principal each payment.  


The programs presented here will calculate:


*  The payment during the interest only term

*  The remaining payment when principal starts becoming due

*  The total cash outflow with the total interest paid, which will definitely be higher than the traditional route


Inputs:


*  INTEREST YEARS?:   The number of years where a loaner pays only interest.   Assume that the interest only payments occur at the beginning of the loan.

*  PRINCIPAL YEARS?:  The number of years where principal is paid.


Example:  For a 5/25 loan:

INTEREST YEARS = 5

PRINCIPAL YEARS = 25


* INTEREST RATE:  The annual interest rate of a loan

* PV:  Amount of the loan (present value)


The calculation assumes that there is no balloon payment (FV = 0).


TI-84 Plus Program:  INTONLY


"EWS 2021-03-13"

ClrHome

Disp "INTEREST ONLY LOAN"

Input "INTEREST YEARS? ",T

Input "PRINCIPAL YEARS? ",Y

Input "INTEREST RATE? ",R

Input "PV? ",P

P*R/1200→U

­-tvm_Pmt(12Y,R,P,0,12,12)→V

Disp "INT ONLY PMT:",U

Disp "REMAINING PMT:",V

Pause 

12(T*U+Y*V)→W

W-P→X

Disp "TOTAL PMTS:",W

Disp "TOTAL INTEREST:",X


Casio fx-CG50 Program:  INTONLY


"EWS 2021-03-14"

ClrText

"INTEREST ONLY LOAN"

"INTEREST YEARS"?->T

"PRINCIPAL YEARS"?->Y

"INTEREST RATE"?->R

"PV"?->P

P*R/1200->U

(-)Cmpd_PMT(12Y,R,P,0,12,12)->V

"INT ONLY PMT:"

U ⊿

"REMAINING PMT:"

V ⊿

12(T*U+Y*V)->W

W-P->X

"TOTAL PMTS:"

W ⊿

"TOTAL INTEREST:"

X


Example


5/30 4% interest rate only.  Loan amount $250,000


INTEREST YEARS: 5

PRINCIPAL YEARS: 30

INTEREST RATE: 4

PV:  250000


Results:  

INT ONLY PMT:  833.3333333

REAMINING PMT:  1193.538239

TOTAL PMTS:  479673.7659

TOTAL INTEREST:  229673.7659


Source:

Kapfidze, Tendayi  "What Is an Interest-Only Mortgage and How Does It Work?"  Edited by Deborah Kearns  LendingTree.  LendingTree, LLC, Charlotte, NC:  2021.   https://www.lendingtree.com/home/mortgage/interest-only-mortgages/  Retrieved 9, 2021


Eddie


All original content copyright, © 2011-2021.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 


Saturday, May 1, 2021

TI-84 Plus CE and Casio fx-CG50: Confusion Matrix, Practice SAT Questions with Mometrix

TI-84 Plus CE and Casio fx-CG50:  Confusion Matrix, Practice SAT Questions with Mometrix 

Confusion Matrix

Introduction


In statistical applications, particularly in medicine, we hear about the infection rates of a disease and tests that are created to designate whether people are infected with the disease.  No test, at least not any that I heard of, is 100% accurate in detecting whether a person is infected with a certain virus.  


Tables can be used to summarize the accuracy of a test, measuring one of four outcomes:


true positive (TP):  the person is infected with a virus and the test detects the virus


false negative (FN):  the person is infected with a virus but the test fails to detect it


false positive (FP):  the test states the person is infected when in reality the person does not have the virus


true negative (TN):  the person is not infected and the test accurate detects the person is healthy (does not have the virus)



One of the common names for this type of table is a confusion matrix. 


Two of the many measurements that can be made from a confusion matrix are called sensitivity and specificity.



Sensitivity is the ratio of true positive results against all of the population that is infected.  


Sensitivity = true positive / (true positive + false negative)




Specificity is the ratio of true negative results against all fo the population that is not infected.  


Specificity = true negative / (false negative + true positive)



The program CONFUSE creates two 3 x 3 matrices (see the illustration below):




Matrix A:  Theoretical confusion table.  This takes into consideration the infection rate and test rate and calculates the expected values.


Matrix B:  Simulated confusion table.  The test uses a random number generator to simulate the chance of whether a person is infected by using the infection rate and whether a person's test is correct by using the test rate.  The results will vary.  



TI-84 Plus CE Program: CONFUSE


"EWS 2021-03-10"

ClrHome

DelVar [A]

DelVar [B]

{3,3}→dim([A])

{3,3}→dim([B])

Disp "CONFUSION MATRIX"

Input "POPULATION? ",N

Input "INFECTION RATE? ",C

Input "TEST RATE? ",T

N*C→[A](3,1)

N*(1-C)→[A](3,2)

[A](3,1)+[A](3,2)→[A](3,3)

[A](3,1)*T→[A](1,1)

[A](3,1)*(1-T)→[A](2,1)

[A](3,2)*(1-T)→[A](1,2)

[A](3,2)*T→[A](2,2)

[A](1,1)+[A](1,2)→[A](1,3)

[A](2,1)+[A](2,2)→[A](2,3)

For(I,1,N)

rand→R

[B](3,1)+(R≤C)→[B](3,1)

[B](3,2)+(R>C)→[B](3,2)

End

[B](3,1)+[B](3,2)→[B](3,3)

For(I,1,[B](3,1))

rand→R

[B](1,1)+(R≤T)→[B](1,1)

[B](2,1)+(R>T)→[B](2,1)

End

For(I,1,[B](3,2))

rand→R

[B](1,2)+(R>T)→[B](1,2)

[B](2,2)+(R≤T)→[B](2,2)

End

[B](1,1)+[B](1,2)→[B](1,3)

[B](2,1)+[B](2,2)→[B](2,3)

ClrHome

Disp "THEORY [A]"

Pause [A]

ClrHome

Disp "SIMULATION [B]"

Pause [B]

Disp "SENSITIVITY",[B](1,1)/[B](3,1)

Disp "SPECIFICITY",[B](2,2)/[B](3,2)


Casio fx-CG50 Program:  CONFUSE


"EWS 2021-03-13"

ClrText

{3,3}->Dim Mat A

{3,3}->Dim Mat B

"CONFUSION MATRIX"

"POPULATION"?->N

"INFECTION RATE"?->C

"TEST RATE"?->T

N*C->Mat A[3,1]

N*(1-C)->Mat A[3,2]

Mat A[3,1]+Mat A[3,2]->Mat A[3,3]

Mat A[3,1]*T->Mat A[1,1]

Mat A[3,1]*(1-T)->Mat A[2,1]

Mat A[3,2]*(1-T)->Mat A[1,2]

Mat A[3,2]*T->Mat A[2,2]

Mat A[1,1]+Mat A[1,2]->Mat A[1,3]

Mat A[2,1]+Mat A[2,2]->Mat A[2,3]

For 1->I To N

Ran#->R

Mat B[3,1]+(R<=C)->Mat B[3,1]

Mat B[3,2]+(R>C)->Mat B[3,2]

Next

Mat B[3,1]+Mat B[3,2]->Mat B[3,3]

For 1->I To Mat B[3,1]

Ran#->R

Mat B[1,1]+(R<=T)->Mat B[1,1]

Mat B[2,1]+(R>T)->Mat B[2,1]

Next

For 1->I To Mat B[3,2]

Ran#->R

Mat B[1,2]+(R>T)->Mat B[1,2]

Mat B[2,2]+(R<=T)->Mat B[2,2]

Next

Mat B[1,1]+Mat B[1,2]->Mat B[1,3]

Mat B[2,1]+Mat B[2,2]->Mat B[2,3]

ClrText

"_Mat _A: THEORY" ⊿

Mat A ⊿

"_Mat _B: SIMULATION" ⊿

Mat B ⊿

"SENSITIVITY:"

Mat B[1,1]/Mat B[3,1] ⊿

"SPECIFICITY:"

Mat B[2,2]/Mat B[3,2]


Example


Population:  N = 200

Infection Rate:  5%  (enter 0.05)

Successful Test Rate: 80%  (enter 0.80)


Theoretical Matrix (Matrix A):

[[ 8 38 46

2 152 154

10 190 200  ]]


Some simulated results (Matrix B, your results will vary):


Simulation 1:

[[ 7 40 47

1 152 153

8 192 200 ]]


Sensitivity ≈ 0.8750

Specificity ≈ 0.7917


Simulation 2:

[[ 5 34 39

1 160 161

6 194 200 ]]


Sensitivity ≈ 0.8333

Specificity ≈ 0.8247


Sources:


"Confusion Matrix" Wikipedia.  Last Edited February 27, 2021. https://en.wikipedia.org/wiki/Confusion_matrix   Retrieved March 9, 2021. 


Texas Instruments "Webinar:  Modeling as a Tool To Make Sense of the World Around Us" Presented by Gail Burrill and Tom Dick, Ph.D.  https://education.ti.com/en/professional-development/teachers-and-teams/online-learning/on-demand-webinars/2021/mar-09-2021-modeling-as-a-tool-to-make-sense  March 9, 2021


University of Nottingham.  "Accuracy Table" https://www.nottingham.ac.uk/nursing/sonet/rlos/ebp/sensitivity_specificity/page_four.html  Retrieved March 9, 2021


SAT Practice Problems with Mometrix


In 2018, I mentioned that I was going to practice some SAT questions (http://edspi31415.blogspot.com/2018/02/).  If you are taking the SAT or want to practice, a place to go is Mometrix Test Preparation.  Mometrix has online practice tests for reading, writing, and mathematics, as well as official Sample tests.  

Check them out here:  https://www.mometrix.com/academy/sat-practice-test/

Their math page which includes a free online practice test:  https://www.mometrix.com/academy/sat-math-practice-test/

Many thanks to George Bigelow for the information and site.


Disclaimer:  This is not a paid advertisement.  


Eddie


All original content copyright, © 2011-2021.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 


Sunday, April 25, 2021

HP 12C: Statistical Signal to Noise Ratio

HP 12C:   Statistical Signal to Noise Ratio


Introduction and The Formula


There are many parameters that can be used to measure signal to noise ratio.   Today's formula will concentrate on the statistical measurements of univariate (1-variable) data.  The signal to noise ratio (SNR) is defined as the inverse of the ratio of the coefficient of variation, or the ratio of the mean to deviation.


SNR = mean / deviation


In the sources listed below (see the Sources section), they define the ratio as:


SNR = mean / standard deviation


However, the sources define standard deviation as:


√( ∑(x_i - mean for i = 1 to n) / (1 - n )


This is the formula for sample standard deviation, and that is the deviation this program will use.


HP 12C Program:  SNR


STEP KEY     KEY CODE

01 x-bar 43, 0

02 STO 0 44, 0

03 s         43, 48

04 RCL 0 45, 0

05 x<>y 34

06 ÷         10

07 GTO 00         43, 33, 00


Notes:


1.  x-bar displays the mean for both x and y data in their respective stacks.  Since we are only interested in the x data, I had to store the mean in R0.

2.  Similarly, calling up the s function displays the standard deviation for both x and y. 

3.  In statistics, only certain registers are available for storing values.  The HP 12C stores the following calculations during statistics:  R1: n,  R2: ∑x, R3: ∑x^2, R4: ∑y, R5: ∑y^2, R6: ∑xy.  


Instructions


1.  Clear the statistical data registers by pressing [ f ], [ SST ].

2.  Enter the data by using [ ∑+ ].

3.  Run the program by pressing [ R/S ].


Examples


Note:  The HP 12C is set to Fix 4 mode for these examples.  


Example 1: 

Data:  10, 35, 76, 49, 52, 56

SNR:  2.0883

(Mean:  46.3333,  Sample Standard Deviation:  22.1871)


Example 2:

Data:  50, 30, 20, 35, 25

SNR:  2.78000

(Mean:  32.0000,  Sample Standard Deviation: 11.5109)


Sources


BYJU'S  "Signal to Noise Ratio Formula"  BYJU'S Classes. 2021. https://byjus.com/signal-to-noise-ratio-formula/  Last Retrieved March 23, 2021  


EasyCalculation.com  "How to Calculate Signal to Noise Ratio (SNR) - Tutorial" https://www.easycalculation.com/statistics/learn-signal-to-noise-ratio.php Last Retrieved March 23, 2021


Wikipedia  "Signal-to-noise" https://en.wikipedia.org/wiki/Signal-to-noise_ratio  Retrieved February 27, 2021


Eddie


All original content copyright, © 2011-2021.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 


Saturday, April 24, 2021

TI-Nspire CX and CX II: Finance Widgets

TI-Nspire CX and CX II:  Finance Widgets


Financial Widgets


The zip file has five widgets:


simple interest widget:  Calculates the total interest paid in a simple interest loan


pi payment widget:  Calculates the payment of a monthly mortgage without a balloon payment.  


piti widget:  Calculates the PITI (payment-interest-tax-insurance) of a mortgage.  Down payment, annual property tax, and annual property insurance are included.


qualified loan amount widget:  Determines the amount of purchase price a buyer can afford.  The standard 28/36 ratio test is used, compares the two methods, and uses the minimum payment to estimate the qualified amount.  


qualified income test widget:  Test whether the proposed PITI and debt payments against a buyer's income  


Instructions


1.  Download the zip file here:  https://drive.google.com/file/d/1cl-yMpcwRHypGa1kdi66ThZs2xf5pPaQ/view?usp=sharing

2.  Save the widget (tns) files to the MyWidgets folder.

3.  Any tns file in the MyWidgets can be opened as a regular document or be added to a document by Insert-Widget.  

4.  When operated as a widget, highlight the entire page by Ctrl+A, pressing [ menu ], selecting 1. Actions, 1.  Evaluate (Enter).  


Eddie


All original content copyright, © 2011-2021.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 


Sunday, April 18, 2021

Swiss Micros DM16L: Advanced Boolean and Factorial (up to 20)

Swiss Micros DM16L:   Advanced Boolean and Factorial (up to 20)


Introduction


The program listing, for the Swiss Micros DM16L and Hewlett Packard HP 16C,  will assign the following functions to the labels:


A:  NAND:   nand(x, y) = not(x and y)

B:  NOR:   nor(x, y) =  not(x or y)

C:  XNOR:  xnor(x, y) = (not x and not y) or (x and y)

D:  Implication:  y → x = (not y) or x

E:  Factorial:  x!  (x is a positive integer up to 20, 64 word size


NAND, NOR, NXOR, and Implication are advanced Boolean functions.  You can check out program code for the HP Prime here:


http://edspi31415.blogspot.com/2020/03/hp-prime-advanced-boolean-functions.html


Program - DM16L/HP 16C


// NAND

001 43,22,A LBL A

002 42,20   AND

003 42,30   NOT

004 43,21   RTN


// NOR

005 43,22,b LBL B

006 42,40   OR

007 42,30  NOT

008 43,21  RTN


// XNOR

009 43,22,C LBL C

010 44,1    STO 1

011 42,30  NOT

012 34      x<>y

013 44,2    STO 2

014 42,30   NOT

015 42,20   AND

016 45,1    RCL 1

017 45,2    RCL 2

018 42,20  AND

019 42,40   OR

020 43,21   RTN


// Implication

021 43,22,d LBL D

022 34      x<>y

023 42,30   NOT

024 42,40   OR

025 43,21   RTN


// Factorial

026 43,22,E LBL E

027 44,32  STO I

028 1      1

029 44,1    STO 1

030 43,22,1 LBL 1

031 45,1    RCL 1

032 45,32   RCL I

033 20      ×

034  44,1    STO 1

035 43,23   DSZ

036 22,1    GTO 1

037 45,1    RCL 1

038 43,21   RTN


Examples


Let:

R1 = 1011 0001

R2 = 1100 1100


Set up: 2-16-0000 (2's complement, 16 bits)


RCL 2, RCL 1, GSB A NAND(R2, R1):  0111 1111*

RCL 2, RCL 1, GSB B NOR(R2, R1): 0000 0010*

RCL 2, RCL 1, GSB C XNOR(R2, R1): 1000 0010*

RCL 2, RCL 1, GSB D R2 → R1:  1100 1110* 

* only the last eight bits 


Set word size to 64:

0 [ f ] [ STO ] (WSIZE)


5 GSB E 5! = 120

9 GSB E 9! = 362880*


* if the word size is insufficient, it will not show 362880 but a weird result as an overflow


12 GSB E   (64 word size)

12! = 4 79001600

Window 1:  4

Window 0:  79001600


20 GSB E

20! = 243 29020081 76640000

Window 2: 243

Window 1: 29020081

Window 0: 76640000


Source for the Advanced Boolean Functions:


John W. Harris and Horst Stocker.  Handbook of Mathematics and Computation Science  Springer:  New York, NY.  2006.  ISBN 978-0-387-94746-4



Eddie


All original content copyright, © 2011-2021.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 


Saturday, April 17, 2021

Fun with the HP 20S (April 17, 2021 Edition)

Fun with the HP 20S (April 17, 2021 Edition)


A Quick Note - Spam Comments 

I noticed that my blog recently had a lot spam comments, especially since the beginning of this year.  Because of this I am considering turning off the ability to leave comments altogether.  If you are going to comment, please be courteous and stay on topic.  No one wants to read the same spam post about off-shore casinos, printers, or scandalous divorce inquiries.

Thank you and now, on with the post.  



Integer Division


The program calculates the quotient and remainder of the division: 


a ÷ b


Instructions:


Enter a, press [ XEQ ] ( F ), enter b.   Get the quotient, press [ R/S ], get the remainder



Program:


01 61,41,F         LBL F

02 21,2 STO 2

03 45        ÷

04 26        R/S

05 21, 1    STO 1

06 74          =

07 21,0      STO 1

08 51,45    IP

09 26          R/S

10 22,0      STO 0

11 61,45    FP

12 55        ×

13 22,1      RCL 1

14 74        =

15 51,33,0         FIX 0

16 61,44    RND   (round)

17 61,34    ALL

18 61,26    RTN



FIX 0, RND, ALL:  round the number in the display to the nearest integer


Examples:


74 ÷ 6  = 12 R 2

Keystrokes:  74, XEQ F, 6, R/S (12) R/S (2)


1576 ÷ 237 = 6 R154


Day Number


This calculates the day number given the month and the date.   A 365-day year is assumed.  


Instructions:

1.  Store month in memory register 1

2.  Store day in memory register 2

3.  Press XEQ A


Program:


01 61,41,A         LBL A

02 22,1      RCL 1

03 31        INPUT

04 2          2

05 61,42    x≤y?

06 51,41,1         GTO 1

07 33          (

08 33        (

09 22,1      RCL 1

10 75        +

11 1          1

12 34          )

13 55        ×

14 3            3

15 0          0

16 73        .

17 6          6

18 34          )

19 51,45    IP

20 65        -

21 6            6

22 3          3

23 74          =

24 21,3      STO 3

25 51,41,2         GTO 2

26 61,41,1         LBL 1

27 33          (

28 33        (

29 22,1      RCL 1

30 65        -

31 1          1

32 34      )

33 55        ×

34 6            6

35 3          3

36 45        ÷

37 2          2

38 34        )

39 51,45    IP

40 74        =

41 21,3      STO 3

42 61,41,2         LBL 2

43 75        +

44 22,2      RCL 2

45 74        =

46 21,3      STO 3

47 61,26    RTN


Examples:


February 16:  2 STO 1, 16 STO 2, XEQ A.  Result:  47

August 22:  8 STO 1, 22 STO 2, XEQ A.   Result:  234


Source:

Duffett-Smith, Peter.  Practical Astronomy With Your Calculator  2nd Ed.  Cambridge University Press: Cambridge.  1979  ISBN 0-521-28411-2


Astronomy:  Geocentric Parallax


The program calculates the quantities ρ sin θ' and ρ cos θ' where:


ρ = distance the observer is from the center of the Earth in meters

θ' = geocentric latitude in degrees


Inputs:


h = height of observer above sea level in meters

L = latitude of the observer in degrees, north is positive


Calculations:


h' = h / 6378140   (estimated radius of Earth is about 6,378 km)

u = atan(0.996647 tan L)

ρ sin θ' = 0.996647 sin u + h' sin L

ρ cos θ' = cos u + h' cos L


Program:


01 61,41,b         LBL B

02 61,23    DEG

03 33          (

04 22,1      RCL 1

05 25        TAN

06 55        ×

07 73        .

08 9          9

09 9          9

10 6            6

11 6          6

12 4          4

13 7          7

14 21,0      STO 0

15 34          )

16 51,25    ATAN

17 21,3      STO 3

18 22,2      RCL 2

19 45        ÷

20 6            6

21 3            3

22 7            7

23 8          8

24 1            1

25 4          4

26 0          0

27 74          =

28 21,4        STO 4

29 22,0      RCL 0

30 55          ×

31 22,3      RCL 1

32 23        SIN

33 75        +

34 21,1      RCL 1

35 23          SIN

36 55            ×

37 22, 4        RCL 4

38 74        =

39 26          R/S

40 22, 3        RCL 3

41 24            COS

42 75          +

43 22, 4      RCL 4

44 55        ×

45 22, 1      RCL 1

46 24          COS

47 74          =

48 61,26      RTN


Registers used:


R1 = L  (input)

R2 = h   (input)

R3 = u

R4 = h / 6378140

R0 = 0.996647


Example:


Input:

L = 45.76° N

h = 53.48 m


54.76 STO 1, 53.48 STO 2, XEQ B

Result:  

ρ sin θ' = .712859241, R/S

ρ cos θ' = .698873028


Source:

Duffett-Smith, Peter.  Practical Astronomy With Your Calculator  2nd Ed.  Cambridge University Press: Cambridge.  1979  ISBN 0-521-28411-2


Eddie

All original content copyright, © 2011-2021.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Monday, April 12, 2021

Spotlight: Jim Cullen - Mathematical Topics

Spotlight:  Jim Cullen - Mathematical Topics 


On today's blog I want to feature Jim Cullen, who has a mathematical web page:


Mathematical Topics Index Page - Associated Calculator Programs


Topics include:


Pi and several series to approximate π

Random Normal Number Generators

Generalized Fibonacci Sequences

A Comparison between Casio fx-115ES and Sharp EL-W516 (2 pdf files)

Diophantine Equations



Cullen also has a page of family's genealogy:  http://members.bex.net/jtcullen515/CullOrig.htm


Check it out,  


Eddie


All original content copyright, © 2011-2021.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 


Sunday, April 11, 2021

Retro Review: Hot Rod Calculator

 Retro Review:   Hot Rod Calculator








Quick Facts:


Model:  8703, Hot Rod Calc

Company:  Mr. Gasket Co/Calculated Industries

Years of Production: 2009 - 2020*

Memory Registers:  1

Batteries:  2 LR-44

Operating System:  Chain

Display:  8 digits, unit indicators 

New Price: $80 retail; can be found on sale or clearance


* I can no longer find the Hot Rod calculator as a new calculator on the Calculated Industries website.  However, the Hot Rod app for both iOS and Android.  


Ladies and Gentlemen, Start Your Engines!


The Hot Rod Calc is a specialty calculator that emphasizes on automotive mathematics, with solvers and applications including:  


*  Air Temperature, Relative Humidity (Moisture), Elevation

*  Vehicle Weight, Elapsed Time (1/4 mile traveled in seconds), MPH

*  Bore, Stroke, RPM, Torque, Engine Displacement

*  Tire Ratio, Gear Ratio

*  Engine Volumetric Efficiency

*  Carburetor Size

*  Vehicle Weight, Horsepower, Elapsed Time

*  Conversions including length, area, volume, temperature, mass, velocity (speed)


You can download a PDF version of the manual here: 


https://documents.holley.com/mr_gasket_instructions_hot_rod_calculator_8703.pdf


The manual has several reference tables:


*  Drag Coefficients depending on the automobile type

*  Holley Jet Chart

*  Jet Orifice Area Conversation Chart


Keyboard


The calculator comes in a bright red Armadillo Gear case.   The keys are bright and colorful, with most of them sporting a warm color palette (red, orange).  The keys are responsive, but have a rubber feel to them.  I believe the keys are made to handle dirt and oils given the target audience of the Hot Rod Calc.


The case has a quick reference guide.


Example Calculations


The calculator is set to U.S. units (default)


Example 1:


Calculate Air Temperature given:

Elevation:  1,284 ft

Air Pressure:  30.12 inHg

Humidity:  33%


1284 [ Elev/ADI ]

33 [ Moisture ]

30.12 [ Conv ] [Air Temp] (Pressure)

[Air Temp],  Result:  55.4211 °F


Example 2:


Find the weight of a vehicle given:

It's horsepower:  426 HP

It's elapsed time:  9.73 sec to run 1/4 mi


426 [ HP ]

9.73 [ ET ]

[ Vehicle Wt ],  Result:  1999.7337 lb


Example 3:


Find the speed, in miles per hour, for an automobile traveling with the following specifications:

1st Gear:  3.26

Final Drive Gear: 3.03

RPM: 5800 (revolutions per minute)

Diameter of the tires: 26 inches


3.26 [ × ] 3.03 [ Gear Ratio ]

5800 [ RPM ]

26 [ Conv ] [ Gear Ratio ] (New Tire Dia)

[ MPH ],  Result:  45.417902  mph


Verdict


If you are into racing, hot rods, and automobiles, and you need a quick mathematics tool, the Hot Rod calculator is worth the investment.  Its user manual is a well written.  Now may be the best time to purchase one before the calculator becomes a rare item.  


Eddie


All original content copyright, © 2011-2021.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 


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