Write rules of "Round off" numbers.

Explanation

In measurement of physical quantity result with near most calculation represent uncertainty in measurement.
Result obtained should have same number of significant digit which are used in calculation. For this following rules are used.
(1) If in significant digit to dropped is less than 5, the number is kept unchanged.
For example, in number 2.753 is round off to three significant digit then it will become 2.75.
If in significant digit to be dropped is more than 5, the preceding digit is raised (increased) by 1.
For example, in number 5.867 digit to be dropped is more than 5 hence then it will become 5.87 or rounded off to 2 digit it will become 5.9.
(3) If insignificant digit is 5 following convention is followed.
If the preceeding digit is even, the insignificant digit is simply dropped.
For example, 2.745 is rounded off to three significant figure become 2.74.
If preceeding digit is odd, it is increased by 1. For example 2.735 rounded off to three significant figure become 2.74.