Question

There are 5280 feet in a mile and 12 inches in a foot. Explain how you can tell quickly if there are more or fewer than 50,000 inches in a mile.

Answer 1

Ten times 5280 is clearly more than fifty thousand. Since there are more than ten inches in one foot, we have even more than ten times 5289 inches in a mile, so there are many more than 50000 inches in one mile.