The non-calculator GCSE maths exam is now out of the way, and you should have your calculator glued to your hand from now on. Even simple calculations you should use the calculator for. You never know what sort of elementary mistakes you can make in the pressurized situation of a GCSE exam. Eliminate as much risk as you can by using the calculator.
In this blog I will explain how to use the table function on your calculator. I will be showing you how to do it on the Casio fx-83GT PLUS calculator that is most commonly used by GCSE students. This same functionality is also available on the Casio fx-991EX CLASSWIZ calculator. I will also explain in which situations this will be useful.
What is the table function?
The table function allows you to input a function of x and return the values you want in one big table.
For example, let’s say that y = x2 – 5x + 8 and you want to know what y is when x = 1 to 5.
You could manually work out y for each value of x, like below:
x = 1 y = 12 – 5×1 + 8 = 1 – 5 + 8 = 4
x = 2 y = 22 – 5×2 + 8 = 4 – 10 + 8 = 2
x = 3 y = 32 – 5×3 + 8 = 9 – 15 + 8 = 2
x = 4 y = 42 – 5×4 + 8 = 16 – 20 + 8 = 4
x = 5 y = 52 – 5×5 + 8 = 25 – 25 + 8 = 8
The table function will give you all these values automatically, so you don’t need to work out each one separately. Let’s see how this works by doing an example.
How to use the table function
First, to find the table function, click on the MODE/SETUP button (circled in red below).
You will then see these options. Press 3 to choose TABLE.
You’ll now see this screen.
At this point, we need to tell the calculator what to populate the table with.
Let’s use the example mentioned earlier, where I wanted to know the values of y = x2 – 5x + 8 for x = 1 to 5.
To achieve this, I’ll need to type f(X) = X2 – 5X + 8 into the calculator.
You can find X on the calculator in red writing above the ) button. To access this, you first need to press the ALPHA button (circled in red below) and then press the ) button (circled in blue below).
Once it’s been typed out, press the = button to confirm.
You’ll then see this screen.
This is where you decide the first value of X that will appear in our table. We want it to be 1 as we wanted to know y when x = 1 to 5.
This defaults to 1, but if you wanted to know y when x = 2 to 5 for example, you’d just need to type 2 and then press =
Press = once the number displayed on the screen is correct, to confirm this selection.
You’ll then see this screen.
This is where you select the last value of x that will appear in your table. We want this to be 5. You can also change this by pressing the number of choice and the pressing = to confirm.
Press = to confirm this selection.
You’ll then see this screen.
The “Step” is the increment for each value of x. In other words, what the values of x go up in. We want this to be 1, as we want our table to contain x-values 1, 2, 3, 4 and 5. These increase by 1.
Again you can change this if you need to. It defaults to 1.
Press = to confirm the selection.
To help you to understand how the Start, End and Step parameters work, let me give some other examples.
If I chose Start = 2, End = 9 and Step = 1, the x-values in my table will be 2, 3, 4, 5, 6, 7, 8 and 9.
If I chose Start = 3, End = 13 and Step = 2, the x-values in my table will be 3, 5, 7, 9, 11 and 13.
If I chose Start = 1, End = 2 and Step = 0.25, the x-values in my table will be 1, 1.25, 1.5, 1.75 and 2.
Once you’ve confirmed the Step, your table will be generated. Because the calculator has a small display, the whole table will not fit on the screen. To view the rest of the table, you can scroll down by pressing the down button.
Pictured below are the values in our generated table (across two screens).
You’ll notice that these values match the numbers I calculated in the previous section, which is good news.
Once you’ve noted down the values of your table, you can exit the table screen by pressing MODE/SETUP and this time choosing the COMP option by pressing 1. Your calculator will then return to normal mode. In general, if your calculator is in a strange mode, you can fix it by following my guide.
When should I use the table function?
The most common use for the table function is for questions where you need to plot graphs. These questions require filling in a table of x and y values and then plotting those values on a graph. So this would be an ideal use for it, especially when you have to plot a quadratic graph (such as our example, y = x2 – 5x + 8). However bear in mind that these types of question can come up in a non-calculator exam so you shouldn’t rely on the table function totally. To practice questions like this, try our worksheet.
You can also use the table function to check nth term formulas that you have worked out to make sure they are correct. If you were asked to find the nth term of a sequence and you got 4n + 5, you could use the table function to generate the first 5 terms of this sequence and check if it matches the question. This would work for both linear and quadratic sequences. To practice questions like this, try our nth term and quadratic sequences worksheets (although remember that quadratic sequences is only examinable on the higher tier exam).
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