Karissa determines the area of her desk by multiplying 45.72 centimeters and 60.95 centimeters. She states that the area is 2786.634 square centimeters. Which best describes the reasonableness of Karissa’s solution?

Question

The solution is unreasonable because 50 times 60 is 3,000, not 2,786.
The solution is reasonable because 50 times 60 is 3,000, which is close to the computed area.
The solution is unreasonable because there are four decimal places in the factors and only three decimal places in the product.
The solution is reasonable because there are four numbers to the left of the decimal in the factors and four numbers to the left of the decimal in the product.

Answer 1

The best description of the reasonableness of Karissa’s solution is:

The solution is reasonable because 50 times 60 is 3,000, which is close to the computed area.

This assessment takes into account that Karissa's approximate calculation (using rounded values) yields a number that is within a reasonable range of her actual calculated area.