Round off and Estimation of Numbers:

There are a number of situations in which we do not need the exact quantity but need only a reasonable guess or an estimate

For example, India drew with Pakistan in a hockey match watched by approximately 51,000 spectators in the stadium and 40 million television viewers worldwide.

Were there exactly 51,000 spectators in the stadium? or did exactly 40 million viewers watched the match on television?

Obviously, not. The word approximately itself shows that the number of people were near about these numbers. Clearly, 51,000 could be 50,800 or 51,300 but not 70,000. Similarly, 40 million implies much more than 39 million but quite less than 41 million but certainly not 50 million.

Estimating outcomes of number situations:

There are many situations where we need to find answers more quickly.
For example, when you go to a fair or the market, you find a variety of attractive things which you want to buy. You need to quickly decide what you can buy. So, you need to estimate the amount you need. It is the sum of the prices of things you want to buy.

A trader is to receive money from two sources. The money he is to receive is Rs. 13,569 from one source and Rs. 26,785 from another. He has to pay Rs. 37,000 to someone else by the evening. He rounds off the numbers to their nearest thousands and quickly works out the rough answer.

In number of situations, we have to estimate the outcome of number operations. This is done by rounding off the numbers involved and getting a quick, rough answer.

The procedure depends on the degree of accuracy required and how quickly the estimate is needed. The most important thing is, how sensible the guessed answer would be.