This applet can be used to introduce and practice multiples, common multiples, the least common multiple and writing fractions with common denominator. It can be used to explore the difference between common denominator and the least common denominator (LCD). Follow the activities below the applet.

1. Finding multiples of a number.

Enter a number in the input box for the first denominator, for example 3.

Click repeatedly on the Add Parts button. Notice what is the number of New Parts when the green light appears and try to predict when it will appear again

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2. Common multiples and the least common multiple.

Enter numbers in the boxes for both denominators, for example 4 and 6.

Click repeatedly on the Add Parts button. Notice what is the number of New Parts when both green lights are on.

Continue to add new parts until both lights are on again.

Discuss the significance of the first appearance of both green lights.

Discuss the significance of the number of new parts in each original division when both green lights are on.

3. Writing fractions with common denominators.

Enter two fractions, for example, 3/4 and 1/6.

Click repeatedly on the Add Parts button until you find the LCD.

Enter two numbers in the input boxes for the numerators so that the two new fractions are equivalent to the original fractions and have the same denominators.

Add more new parts until you find another common denominator.
Enter the numerators of the equivalent fractions using this new denominator.