Multiplying Fractions
Multiply the tops, multiply the bottoms.
There are 3 simple steps to multiply fractions
- 1. Multiply the top numbers (the numerators)
- 2. Multiply the bottom numbers (the denominators)
- 3. Simplify the fraction if needed
Example:
Step 1. Multiply the top numbers:
12 × 25 = 1 × 2 = 2
Step 2. Multiply the bottom numbers:
12 × 25 = 1 × 22 × 5 = 210
Step 3. Simplify the fraction:
210 = 15
With Pizza
Here you can see it with pizza ...
Do you see that half of two-fifths is two-tenths?
Do you also see that two-tenths is simpler as one-fifth?
With Pen and Paper
And here is how to do it with a pen and paper (press the play button):
Another Example:
Step 1. Multiply the top numbers:
13 × 916 = 1 × 9 = 9
Step 2. Multiply the bottom numbers:
13 × 916 = 1 × 93 × 16 = 948
Step 3. Simplify the fraction:
948 = 316
(This time we simplified by dividing both top and bottom by 3)
The Rhyme
♫ "Multiplying fractions: no big problem,
Top times top over bottom times bottom.
"And don't forget to simplify,
Before it's time to say goodbye" ♫
Fractions and Whole Numbers
What about multiplying fractions and whole numbers?
Make the whole number a fraction, by putting it over 1.
Example: 5 is also 51
Then continue as before.
Example:
Make 5 into 51 :
23 × 51
Now just go ahead as normal.
Multiply tops and bottoms:
23 × 51 = 2 × 53 × 1 = 103
The fraction is already as simple as it can be.
Answer = 103
Or you can just think of the whole number as being a "top" number:
Example:
Multiply tops and bottoms:
3 × 29 = 3 × 29 = 69
Simplify:
69 = 23
Mixed Fractions
You can also read how to multiply mixed fractions