Adding and Subtracting Fractions with the Butterfly Method

Butterfly

Butterfly Fractions

To add or subtract fractions the butterfly way,

1. Write the fractions side-by-side as usual and draw two wings along the diagonals made by the numerator of one fraction and the denominator of the other fraction and draw an antenna on each wing.

2. As suggested by the wings, that look like a multiplication sign, multiply the numbers in each wing and put the product in the antenna for the wing.

3. Think or say: “This poor butterfly needs a body.” To give it a body, connect the bottom parts of the wings with a body-like loop and multiply the two denominators it connects, putting the product inside the body.

4. Add or subtract the numbers in the antennae in keeping with what is being done to the fractions and put the result over the number in the body.

5. If necessary, reduce or simplify the result.

The butterflies above for 3/4 + 2/5 and 3/4 – 2/5 illustrate the procedure. The only difference in subtracting the fractions versus adding them is in the last step where the numbers in the antennae are subtracted instead of added. via

28 thoughts on “Adding and Subtracting Fractions with the Butterfly Method”

  2. NOOOOOO Please stop teaching this…. This is why students in HS don’t know how to do this. No conceptual knowledge.

    Reply
  5. Pingback: Add/Subtract Fractions using "Butterfly Method" | Pearltrees

Leave a comment