3.3.4 Relationships Among Operations
Multiplication can be thought of as repeated addition. For example, we know that . You probably memorized this multiplication fact as a child, but why is this true? Well, we can think of multiplication as a direction to add the first number to itself the second number of times. So, is telling us to add 2 to itself 3 times: .
Similarly, division can be thought of as repeated subtraction. For example, we know that . The answer is 5 because 5 is the number of times you subtract 4 from 20 to arrive at zero:
Let’s review how to carry out multiplication and division of larger numbers as well as hone our mental math skills by watching this seven-minute video. NOTE: At 3:12 the professor incorrectly calls the dividend the quotient. Even teachers make mistakes!