An apartment has 4 bedrooms. Each bedroom has 3 bookcases. How many bookcases are there in the apartment?

Using addition, you can argue that there are 12 bookcases in the apartment.
( 3 + 3 + 3 + 3 = 12)

However, the problem can be solved faster by doing a multiplication of 3 and 4 since 3 × 4 = 12

In general, multiplication gives the same answer as repeated addition.