A rectangular room measures 3.8 meters in length and 4.9 meters in width. Jana multiplies both numbers together. Which expression would be best for her to use to check the reasonableness of her decimal multiplication?

Question

3 times 4
3 times 5
4 times 4
4 times 5

Answer 1

To check the reasonableness of her decimal multiplication, Jana should use a simple expression that gives a rough estimate of the area of the room based on the dimensions given.

The original dimensions are 3.8 meters (length) and 4.9 meters (width). The closest simple whole numbers for these dimensions are 4 meters and 5 meters.

Among the options provided, the best choice for checking the reasonableness would be:

4 times 5

This expression gives an area of 20 square meters, which is a simple and reasonable approximation for the product of 3.8 and 4.9.