Question: What is Rounding ?


A calculator often gives the result of a calculation to many more digits than is required. Approximating to the answer by giving it to a smaller number of significant figures or decimal places is known as rounding off.

The result of rounding is a shorter number having fewer non-zero digits yet similar in magnitude. The result is less precise but easier to use. The last digit to be ignored is the clue to how to round off the last digit kept. If it is 5 or more, the last digit is kept is increased by 1, if less than 5, it is unchanged. The rounded number must be as near to the original as possible.

For example, 362.84518
362.8 when rounded to 1 decimal place;
363 when rounded to the nearest whole number;
362.85 when rounded to 5 significant figures;
360 when rounded to 2 significant figures.
73 rounded to the nearest ten is 70, because 73 is closer to 70 than to 80.