Exact numbers need not be measured. They can be counted. Conversion factors and countable units come under exact numbers. Measured quantities are measured using a device.
1) Number of microseconds in a week -Exact as it need not be measured. It can be estimated using the conversion factors between microseconds, seconds, minutes, hours, days and week.
2) Number of inches in a mile - Exact number as it is an established conversion factor.
3) The mass of a paper clip - Measured number as it has to measured using a weighing balance.
4) The number of pages in a book - Exact number as it is not measured. It can be counted.
5) Surface area of the dime-Measured number as it has to be measured.
6) The number of ounces in a pound-Exact number as it is a constant value.
