Decimal numbers are numbers which are written in form of decimal and whole part. Part written after decimal sign is called as decimal numbers. On the other hand we say that numbers which do not have any digits in tenth place, hundredth place and so on … are called as Whole Numbers.
We come across certain problems where we need to round off decimal numbers to whole numbers. It is also called estimating number to the nearest whole number.
For rounding decimals to whole numbers, we will look at digit at the tenth place. If the digit at tenth place is less than 5, then figures at decimal part are eliminated and whole number is the result.
For example: If we write the number 35.238, here digit at tenth place is 2, which is less than 5, so round off result will be 35.
On other hand we say that if digit at tenth place is 5 or more than 5, then we say that successor of whole number is the result.
So if we will write the number 345.63, we find that digit 6 is at tenth place. Round off of the number 345.63 will be 345 + 1 = 346.
While estimating a number to whole number, we basically need to take care if decimal part of number is less than or more than half of the given number. It can only be checked by digit at tenth place. Only if digit at tenth place is less than 5, it means decimal part of number is less than half.