Analysis: This topic mainly examines multiplication in mathematical operations, as follows:

According to the meaning of the question, Cong Cong lives on the sixth floor, so a * * * has five steps; Walking back and forth four times a day, the number of steps per day is eight, and because Cong Cong has to walk 18 steps from the first floor to the second floor, the number of steps he has to walk every day is 18×5×8=720 steps.

Extended data:

Multiplication can also be seen as calculating the objects arranged in a rectangle (integer) or finding the area of a rectangle with a given side length. The area of the rectangle does not depend on which side is measured first, which shows the exchange property. The product of two measured values is a new type of measurement, for example, multiplying the length of two sides of a rectangle to get its area, which is the theme of size analysis.

Multiplying a number with multiple decimal places is troublesome and error-prone. The universal logarithm was invented to simplify this calculation. The slide rule allows numbers to be quickly multiplied by about three digits of precision. Since the early 20th century, mechanical calculators, such as Marchant, have automatically multiplied as many as 10 digits. Modern electronic computers and calculators greatly reduce the need for manual multiplication.