INSTRUCTIONS

The following image was made from Subtract Fractions:

The parts of a subtraction example are the minuend, the subtrahend, and the difference.

When the program starts, you will be asked to identify the minuend in the first row and then the subtrahend in the second row. The program will not continue unless the minuend and subtrahend are correctly identified. You will then be asked to find the difference.

You can see from the picture that the minuend is 3 1/4 units in length and the subtrahend is 2 5/8 units in length. The difference is what is left after removing the amount of blue circles in the second row from the amount of red circles in the first row. In many examples, you can arrive at the difference by looking at the picture. For example, after removing the two whole circles, you are left with 1 1/4 red circles. Removing the 5/8 circle from the 1 1/4 circle that is left in the minuend will leave 1/4 + 1/4 + 1/8 circle for the difference of 5/8 circle.

To calculate the difference,  all examples can be written in fraction form first.  If the denominators are unlike, each fraction must be written with a common denominator. Once each fraction has a like denominator the difference may be found by subtracting the numerators.

The program COMPARE FRACTIONS shows how to find the common denominator.

Writing the minuend and subtrahend in fraction form, the example would look like this: :

Or, when the numerator of the subtrahend is larger than the numerator of the minuend you may rewrite the minuend to subtract. Some texts call the procedure "borrowing". This is illustrated below:

Notice how 3 2/8 is renamed as 2 10/8 so that the numerators can be subtracted.

You may prefer to work vertically: