Almost all numbers that we use in daily life are decimal numbers. The place value of each digit is ten times the place value of the digit to its right. And that is all that is required of decimal numbers. A decimal point is not necessary.
1.20 has the same value as 1.2 and they are both decimal numbers
explain why it is important to line up decimal numbers by their place value when you add or subtract them
9 and 3 are in the 14th and th decimal place for the value of pi.
They are written as numbers usually are. The place value of the digit immediately to the left of the decimal point is ones and the place value of all other digits is ten times the value of the digit to their right.
They are fractions of a centimetre.
The decimal point is just a point. It has no numbers or value associated with it!
The range is the largest value minus the smallest value from a set of numbers.
A decimal number is one way of representing numbers where each place for a digit has a place value that is ten times that of the place to its right. Most all the numbers that you familiar with (judging from your question) will be decimal numbers. A decimal number need not be a [decimal] fraction.