1 inch = 2.54 cm or

1 gallon = 231 cubic inches or

1 foot = 12 inches

or

numbers that come in integers and are not likely to be available in amounts smaller than integers. When you ask for seating in a restaurant, the number of people is an integer, an exact number.

Measured numbers are an estimated amount, measured to a certain number of significant figures without the benefit of any natural unit or a number that comes from a mathematical operation such as averaging. You would get a measured number from using a meterstick to find the length of a board or using a graduated cylinder to find the volume of a liquid. Average numbers of people would make a measured number, even though people naturally come only in integers. The average family in the U.S. has 2.37 children.

I’m so good at following directions.