A decimal number is divided in two parts; one part is before the decimal point and another part is after the decimal point. Lets see is a decimal a whole number?
We say that decimal numbers are the numbers which are expressed in the form such that a decimal point appears with the number in such a way that the number is divided into two parts, one part appears before a decimal point and the another point appears after a decimal point. The only difference between the digits placed before and after the decimal is of their place value. So we say that the place value for the numbers appearing before the decimal are in the form of ones, tens, hundreds and so on starting from the decimal to the left. On other hand the digits appearing after the decimal point have place value of tenth, hundredth, thousandth, starting from the decimal to the right side. Any of the numerical value can appear at these different places and decimal number is formed. If we take a number say 123.56.
Here we observe that the number before the decimal is the whole number and the number placed after the decimal point is the decimal part of the number. Now we take a situation, where we observe that there is a whole number only. Now if we write the whole number say 342 under the place values of the decimal number, we observe that the digits after the decimal numbers is 0 0 0, and the number 342 will be written as 342.00. So we come to the conclusion that the whole number can also be expressed in form of the decimal number, where the decimal part will be zero, which will be written after decimal point.