The arithmetic calculation involving observed/measured quantities should be such that the resulted quantity cannot be more precise than the original observed/measured values. Thus, the final result should not have more significant figures than the original data from which it has been derived.
In order to achieve such result, following rules for arithmetic operations are required to be followed:
• In addition or subtraction, the final result should be rounded off in such a way as to retain as many decimal places as are there in the original number with the least decimal places.
For example
