In common use, a decimal refers to part of a whole number. The numbers to the left of a decimal point represent whole numbers, and each number to the right of a decimal point represents a fractional part of a power of one-tenth. For instance: The decimal value 1.24 indicates 1 whole unit, 2 tenths, and 4 hundredths (commonly described as 24 hundredths).
The leading digit of a decimal number less than one is the first digit to the right of the decimal point that is not a zero.
To round is to reduce the number of non-zero digits in a number while keeping the overall value of the number similar.