What is Decimal

So, what is decimal?

Decimal is just another way to write fraction (or mixed number).

Decimal has two parts: integer part and fractional part (also called decimal part). Here you can see strong analogy with mixed number.

Notation: integer and fractional parts are separated by the decimal point.

For example, in decimal 523.45, 523 is integer part and 45 is fractional part.

If decimals are so similar to mixed numbers, why do we need them?

There are several reasons for that:

It is easier to perform addition and subtraction of decimals (actually they can be added/subtracted just like integers).
Comparing decimals is easier than comparing fractions.
When they are written, they fit into one line of text just like integer numbers.

Sometimes you can see something like .432. There is no integer part. It just means that integer part equals 0, so .432 is same as 0.432.