Parts of the world, including the United States, still employ unit systems that are not decimal based. For example:
There are 12 inches in foot, and most measuring tapes and ruler use fractions (1/2, 1/4, 1/8, 1/16 and 1/32)
There are 5,280 feet in a mile.
There are 1, 760 yards in a mile.
There are 60 minutes in an angle of a degree, and 60 seconds of angle in a minute.
Likewise, there are 60 minutes in an hour, 60 second in a minute.
The conversion of combinations of these is simple but easy to make a mistake. This calculator suite is for the purpose of making the conversion to decimal (base 10) values.