Occasionally you will work on multi-step problems in which you obtain a number, and need to use that number again in a later step of the problem. If that happens, you can write the number down, or you can memorize it, OR you can use the TI-30X II memory functions to remember the number for you.

The TI has 5 memory locations named A, B, C, D, and E, so you can store up to five numbers.

Let's suppose you wanted to store the number 142857. You would do it like this:

1. Enter 142857 on your calculator
2. Press STO> (right above the ON button
3. Notice that A is underlined on the screen. 
4. Press ENTER to store the number in memory A

You can also store the result of a calculation. For example, if you typed 1 ÷ 4, and then followed steps 2 through 4 above, the calculator would have 1/4 or 0.25 in memory A.

Storing a number in other memory locations is easy; when you see the screen that shows locations Athrough E, simply use the right arrow key until the proper location is underlined. Then press ENTER

All of this is great, but how do you use those numbers you've stored?

That's where the MEMVAR button comes into play. Press MEMVAR, and you will see that list of memory locations. If A is underlined, when you press ENTER, the letter A will appear on your screen. You can now use that A as a symbolic representation of your number in any calculation.

For example, store the number 27 in A and the number 3 in B. Now we can use memory to perform the operation 27 ÷ 3:

1. Press MEMVAR, select A and press ENTER
2. Press ÷
3. Press MEMVAR, select B and press ENTER
4. You should now see A ÷ B on your screen.
5. Press ENTER again to do the calculation.

Mostly, you won't use the memory functions to store numbers like 27 and 3; you'll be more likely to use it for large numbers, numbers with many decimal places, or scientific constants that you'll want to use again and again.

For problems 1 - 5 below, put the following into your memory:
A: 1 ÷ 7
B: 999999
C: 8 ÷ 9

For problems 6 - 10 below, put the following into your memory:
B: 161051
C: 14641
D: 1331