Multiplying fractions - Salisbury University



Multiplying fractions

We will be using the applet at:

for this activity so go ahead and open it.

All together

Notice that there are 2 sliders. One on the horizontal and the other on the vertical. These set the numerators of the fractions that you want to multiply. To set the denominators, use the double blue arrows that are above the sliders.

1. Set up the problem 1/3 x 2/5.

2. The algorithm for multiplying 2 fractions is “multiply the tops and put over the product of the bottoms”. Where is this algorithm displayed in the colors?

3. Why do we end up with 15 boxes?

4. Notice that the text says, “one-third of two fifths”. How does this applet show us that 1/3 x 2/5 is one third of two fifths?

5. If you set up the problem ¾ x 4/5, what kinds of boxes will the applet draw?

On your own

1. Try out at least 6-7 of your own example products.

2. What is the smallest quantity that can be displayed as a factor in a product?

3. What is the largest quantity that can be displayed as a product?

4. In this applet, what is the difference between 2/3 x ½ and ½ x 2/3?

5. How does this applet use a common denominator for the calculated products?

6. Does this applet use a least common denominator?

7. There are 3 other fraction applets at :

Explore at least one of them. Be ready to share a strength and weakness with the class and when you could use the applet in any of your classes.

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