The answer to 7x8 is 56. The multiplication is the same as adding 7 to itself eight times, or adding 8 to itself seven times.
Multiplication.com offers a helpful graphic with aquariums. If a student has seven aquariums and each aquarium has eight fish, the student has 56 fish. The student is then walked through how to solve the problem. Although multiplication problems such as these can be figured out the long way, it is sometimes easier to memorize them to refer back to later. The ones easiest to remember are 1x1 all the way through 10x10. Numbers in the double digits start to get difficult to memorize.