You already know that when you multiply a whole number by another whole number, the answer is a larger number. But when you multiply a fraction by another fraction the answer is smaller! Look at the top picture – if you have 2/5 of a pizza left and you need to share it equally with your brother, how much of the original pizza do you get? How can you add 1/3 and 1/6 of a pizza?
Adding and Subtracting fractions – BBC Bitesize
Multiplying and dividing fractions – BBC Bitesize
How to Add and Multiply fractions – WikiHow