A decimal number can be defined as a number whose whole number part and the fractional part is separated by a decimal point. The dot in a decimal number is called a decimal point. The digits following the decimal point show a value smaller than one. IN short, a decimal is a fraction written in a special form. Instead of writing 1/2, in decimal it is written as 0.5, where the zero is in the ones place and the five is in the tenths place. Decimal comes from the Latin word decimus, meaning tenth, from the root word decem, or 10.