Get Prime Factors on the TI-83

This page demonstraes the use of the GETPRIME program on the TI-83. This program asks a user for a whole number and then the program determines the prime factorization of that number. The program produces a "nice looking" output. In order to do this the program needs to use another program called TOSTR. The listing of that program is given as

Listing of the TOSTR program for the TI-83.

To download, right-click on tostr.83p.

The listing of the GETPRIME program follows:

Part One of the GETPRIME listing for the TI-83	Part Two of the GETPRIME listing for the TI-83

To download the GETPRIME program for the TI-83 right-click on getprime.83p

The following images and discussions cover the use of the GETPRIME program on the TI-83.

Figure 1 In Figure 1 we have moved to the program menu via the key. Furthermore, on that menu we want to move the highlight to point to the GETPRIME program. The calculator used for Figure 1 had that program as the first entry. Therefore, we did not have to move the highlight via the cursor keys.
Given that we have highlighted the GETPRIME program, we can move to Figure 2 by pressing the key
Figure 2 The calculator has responded by pasting the command to run the selected program, in this case GETPRIME, onto the screen. We press the key again, this time to tell the calculator to actually run the program.

Figure 3 The program starts by announcing its name and then by asking us for a number. In Figure 3 we have responded by entering the value 72 via the key sequence.
As usual, we press the key to have the calculator accept our value and to start processing it.

Figure 4 The result of the program is shown in Figure 4. The calculator has factored 72 into (2³)(3²) which the calculator displays as At this point the calculator is in a paused condition; note the series of dots in the upper right corner of the calculator screen. We press key to do another problem.

Figure 5 In Figure 5 we ask the calculator to factor 4704, and the result is 2⁵*3*7²

Figure 6 Figure 6 demonstrates factoring 169400. The result is 2³*5²*7*11² however, we can not see all of the answer in Figure 6. Because the calculator is in a paused condition after displaying the answer we can use the cursor keys to move the display to the right. Doing so will shift the display to that seen in Figure 7.

Figure 7 Here we can see the rest of the answer started in Figure 6.
Having seen the full answer we can press the key again to move to a new problem.

Figure 8 Figure 8 shows the process of factoring 25487584. It is important to point out that it will take the calculator a while to produce that answer. An examination of the algorithm given above shows that the calculator will have to test all of the odd numbers between 5 and the square root of 796,487. Thus, the calculator tries to find a new factor by trying the odd numbers between 5 and 892. It will take the calculator a while to do this.
One last issue is that of stopping the program. In this case we can break out of the program by pressing the key. The result is given in Figure 9.

Figure 9 In response to pressing the "ON" key, the calculator gives us the option of "Quiting" the program or "Going To" the program editor and, more specifically, to the line in the program that was being performed when we hit the "ON" key. Our interest is to quit the program. Therefore, we press the key to select the highlighted option.

Figure 10 Figure 10 shows the calculator having returned to normal mode. Note that the results of the program are still on the screen, but that the program is no longer running.

Figure 1	In Figure 1 we have moved to the program menu via the key. Furthermore, on that menu we want to move the highlight to point to the GETPRIME program. The calculator used for Figure 1 had that program as the first entry. Therefore, we did not have to move the highlight via the cursor keys. Given that we have highlighted the GETPRIME program, we can move to Figure 2 by pressing the key
Figure 2	The calculator has responded by pasting the command to run the selected program, in this case GETPRIME, onto the screen. We press the key again, this time to tell the calculator to actually run the program.
Figure 3	The program starts by announcing its name and then by asking us for a number. In Figure 3 we have responded by entering the value 72 via the key sequence. As usual, we press the key to have the calculator accept our value and to start processing it.
Figure 4	The result of the program is shown in Figure 4. The calculator has factored 72 into (2³)(3²) which the calculator displays as At this point the calculator is in a paused condition; note the series of dots in the upper right corner of the calculator screen. We press key to do another problem.
Figure 5	In Figure 5 we ask the calculator to factor 4704, and the result is *2⁵37²*
Figure 6	Figure 6 demonstrates factoring 169400. The result is *2³5²711²** however, we can not see all of the answer in Figure 6. Because the calculator is in a paused condition after displaying the answer we can use the cursor keys to move the display to the right. Doing so will shift the display to that seen in Figure 7.
Figure 7	Here we can see the rest of the answer started in Figure 6. Having seen the full answer we can press the key again to move to a new problem.
Figure 8	Figure 8 shows the process of factoring 25487584. It is important to point out that it will take the calculator a while to produce that answer. An examination of the algorithm given above shows that the calculator will have to test all of the odd numbers between 5 and the square root of 796,487. Thus, the calculator tries to find a new factor by trying the odd numbers between 5 and 892. It will take the calculator a while to do this. One last issue is that of stopping the program. In this case we can break out of the program by pressing the key. The result is given in Figure 9.
Figure 9	In response to pressing the "ON" key, the calculator gives us the option of "Quiting" the program or "Going To" the program editor and, more specifically, to the line in the program that was being performed when we hit the "ON" key. Our interest is to quit the program. Therefore, we press the key to select the highlighted option.
Figure 10	Figure 10 shows the calculator having returned to normal mode. Note that the results of the program are still on the screen, but that the program is no longer running.