Diffy
When Diffy opens, there are four black numbers placed at the corners of a black square. Your first goal is to fill in the four blanks in the blue circles in the middle of each side of the black square.
Start with any side of the black square and click in the blank in the blue circle on that side and type in the difference of the black numbers on that side (the larger black number less the smaller one). So if the black numbers on the top side of the black square were 7 and 12, we would type 5 (= 12 – 7) in the blue circle between the 7 and the 12.
When you have typed in the correct difference, either press Enter or move the cursor and click in another blue circle. Your difference will then appear as a blue number in the circle. If the difference you type is not correct, when you Enter, the blank will remain and you can type in the correct difference.
When the four blue circles have all been filled correctly, blanks will appear in circles in the next inner square. You need to continue filling in the blanks until you complete all the squares. When you are done, the whole screen color will flash to show that you have correctly completed Diffy.
After you have completed Diffy with one set of numbers, you can choose and the computer will give you another starting set of black numbers, or you can click and enter any set of four black numbers you choose.
Question
What kinds of patterns can you see in the purple numbers when you complete Diffy?
Will you always get some zeros in the purple numbers, or a set of four purple numbers that are all the same, or two pairs of matching purple numbers?
Experiment with some from the computer, or try your own, using the button.
Options
You can choose to work with:
When working with Fractions, the difference of two fractions is a fraction that can be written in many different ways. Type in both the numerator and denominator before pressing Enter, but you can write the fraction in most any equivalent form. A difference of zero can be written as 0/1.