An airplane flight from Houston, Texas to Rome, Italy is 5,686 miles.  Estimate the distance between the two cities as the product of a single digit number times a power of 10.

One way to estimate the distance between Houston and Rome as the product of a single digit number times a power of 10 is:

5 x 1000 = 5000 miles.

This gives an estimate of 5,000 miles between Houston, Texas and Rome, Italy.