Rounding off is a process of simplifying a number by keeping its value but making it closer to the next number. It is a type of estimation that is used in everyday life and in subjects like Mathematics and Physics. Rounding off is done for whole numbers and decimals at various place values like hundreds, tens, tenths, etc. . The number of significant figures in a result is simply the number of figures that are known with some degree of reliability, and rounding off is done to preserve the significant figures.

The process of rounding off involves identifying the digit present in the place value you want to round to, and then checking the digit to the right of it. If the digit to the right is less than 5, the digit you want to round to remains the same. If the digit to the right is 5 or greater, the digit you want to round to is increased by 1.

For example, if you want to round off 3.1416 to the nearest hundredth, you would look at the digit in the thousandth place, which is 6. Since 6 is greater than 5, you would increase the digit in the hundredth place, which is 4, by 1. The final answer would be 3.14.

In summary, rounding off is a process of estimation that is used to simplify numbers while preserving their significant figures. It involves identifying the digit in the place value you want to round to and checking the digit to the right of it to determine whether to round up or down.