Rounding off numbers is an easy way to remember specially big numbers involving 6 or 7 digits or even more. It is also an easier way to remember decimal numbers. Rounding off numbers can be done to nearest tens, hundreds or thousands as needed.
Practical application or necessities of rounding off:
This rounding off numbers finds a wide application in our day to day life.
There are certain rules that are followed while rounding off numbers
Rule I: When a number ends with 5, 6, 7, 8, 9 then we round it off to the next nearest tens.
48 will be rounded off to 50
15 will be rounded off to 10
Rule II: When a number ends with 1, 2, 3, 4 then we round it off to the previous nearest tens.
42 will be rounded off to 40
24 will be rounded off to 20
Now this rounding off is case specific. That is we have to confirm what are we rounding off to?
Rule III: If we are rounding to nearest 10 tens then 5 is the mid position. Number ending with 5 or more should be rounded off to next nearest tens
35 will be rounded off to 40
Rule IV: If we are rounding off to nearest hundreds then also we need to find the mid position.
Round off 437 to nearest hundreds
In this case we need to find the two hundreds between which 437 lies. We know that 437 lies between 400 and 500. The mid position between 400 and 500 is 450. So we need to check whether the number given (here 437) is more than 450 or less than 450. If the given number is 450 or more then we would round the number to 500 and if it is less than 450 then we will round it off to 400. In this example 437 will be rounded off to 400
Rule V: If we are rounding off to nearest thousands we need to find the mid position
Round off 4750 to nearest thousands
The two thousands between which 4750 lies is 4000 and 5000. The mid position is 4500. We know that if a number is equal to or more than mid position then slide it to next thousands, hundreds or tens (as required). Here we need to round off to nearest thousands hence it will be 5000 as 4750 is greater than mid value (4500)