This visual method of multiplying fractions
was something that was shown to me last week
by the girls I tutor. Like most people I learned
to multiply fractions by multiplying numerator
by numerator, and denominator by denominator.
That's pretty much the gold standard of fraction
multiplication.
This method gives a visual sense of what it means
to multiply fractions. For our example we'll use:
2/5 x 1/3=
Draw a square. Divide in into three vertical portions
and color in one of the thirds. This represents 1/3.
For a real world styled word problem, think of this as
a brownie pan with only one third of the brownies
left in it.
Next, we represent the 2/5. Divide the square
horizontally into five portions. Using a different color,
fill in two of the fifths. The two colors will overlap,
this is a good thing.
For the word problem, think some comes and eats
2/5ths of the remaining brownies. How much of
the pan of brownies did they eat?
For our answer, count the total number of rectangles.
This number is our denominator. So for our problem,
this number is 15. The numerator is the number
of rectangles where our colors overlap. Here that
would be 2. So our answer is 2/15, or 2/15 of the
entire pan of brownies.
So, 2/5 x 1/3 = 2/15