Random Number Generator

The TI-82 and TI-83 graphing calculators have a random number operation available under the MATH-PRB menu.  The random number operation, 'rand', generates a random number greater than zero (0) and less than one (1).  The random number is generated from an algorithm that is stored in the calculator.  The random number is generated from an integer seed value.  The randomness of the number generated is less controlled if you do not 're-seed' the generator every time you use the random number operation. 

 
Steps for generating a random number on the TI-82 and TI-83: 

1. Press , , , , and 1: rand.  This will return  "rand"  at the cursor location on the view screen. 

2. Press  to execute the program.  A random  number will be displayed on the right side of the display.  The amount of decimals displayed will correspond to the mode the calculator is placed in.  For example, if the calculator is in the 'floating' decimal mode, there will be nine digits displayed after the decimal.  If the calculator is in the 'three' decimal mode, there will be three digits displayed after the decimal. The view screen will look like the image below.  Remember, since these are random numbers, the actual numbers listed on your calculator may not match the image below. rand.gif (374 bytes)  

The TI-83 calculator also has three additional random number operations, the random integer generator, the random number generator from the Normal distribution, and the random number generator from the Binomial distribution.  All three of these operations are found in the MATH-PRB menu. 

Steps for generating a random integer on the TI-83:  This operation generates and displays a random number within a range designated by a lower bound and an upper bound. 

1. Press , , , , and 5: randInt(.  This will return "randInt(" at the cursor location on the view screen. 
 
2. To specify a lower bound, upper bound, and a desired amount of generated numbers, enter the lower bound, then the upper bound, and then the number of desired random numbers to be generated separated by commas and a closing parenthesis.  Example: To generate six random numbers between two (2) and fifteen (15), the entry should look like this: 
randInt(2, 15, 6).  Pressing  after the entry executes the program. The view screen should look like this image.  Remember, since these are random numbers, the actual numbers listed on your calculator may not match the image below.  randint.gif (434 bytes)

Steps for generating a random real number from a specific Normal distribution:  This choice requires the user to enter the mean and standard deviation, as well as the number of desired random numbers to be generated. 

1. Press , , , , and 6: randNorm.  This will return "randNorm(" at the cursor location on the view screen. 
 
2. To specify a mean, standard deviation, and a desired amount of generated numbers, enter the mean, then the standard deviation, and then the number of desired random numbers to be generated separated by commas and a closing parenthesis.  Example: To generate four random numbers from a Normal distribution with a mean of thirty-two (32) and five (5), the entry should look like this: randNorm(32, 5, 4).  Pressing  after the entry executes the program. The view screen should look like this image.  Remember, since these are random numbers, the actual numbers listed on your calculator may not match the image below.

 randnrml.gif (455 bytes)randnrm2.gif (452 bytes)

The screen on the left is the first view that the calculator provides to the user.  The screen on the right is the view after using the right arrow to view the numbers off the screen.

Steps for generating a random integer from a specific Binomial distribution:  
This choice requires the user to enter the number of trials (must be > 1) and the probability of success (probability must be greater than or equal to zero and less than or equal to one), as well as the number of desired random numbers to be generated. 

1. Press , , , , and 7: randBin.  This will return "randBin(" at the cursor location on the view screen. 
 
2. To specify the number of trials, the probability, and a desired amount of generated numbers, enter the number of trials, then the probability, and then the number of desired random numbers to be generated separated by commas and a closing parenthesis.  Example: To generate five random numbers from a Binomial distribution with seven (7) trials and a probability of twenty percent (.20), the entry should look like this: randBin(7, .20, 5).  Pressing  after the entry executes the program.  The view screen should look like this image.  Remember, since these are random numbers, the actual numbers listed on your calculator may not match the image below.  

randbin.gif (451 bytes)randbin2.gif (447 bytes)

The screen on the left is the first view that the calculator provides to the user.  The screen on the right is the view after using the right arrow to view the numbers off the screen.