We do estimation so that calculation gets easier.
Estimation is done when you don’t require exact answer and approximate calculation is sufficient for you.
For example:
Population of City A is 55,923
Population of City B is 67,432
And we are asked to find total population of City A & B;
So we are required to calculate ==> 55,923 + 67,432
This calculation will require you to take out pen and paper for exact calculation
But in case if you need approximate answer, you should use estimation of numbers:
Closest estimate of 55,923 is ===> 56,000
Closest estimate of 67,432 is ===> 67,000
So Total Population is===> 56,000 + 67,000 ===> 1,23,000 (calculated easily)
From the above example, i hope its clear how concept of estimation is useful in practical life. Let us now understand how to do estimation.
Estimate Nearest Tens
A. Estimation of number 56
Suppose you are given number 56 and you have to find its estimation to its nearest tens
STEP 1:
Find the nearest round number present in tens places
For number 56, there are two round number present at tens places 50 and 60
STEP 2:
Out of 50 and 60, select the one which is nearest.
Hence for number 56, number 60 is the nearest and hence it is the best approximation for tens place
B. Estimation of number 97 to nearest tens
STEP 1:
Find the nearest round number present in tens places
For number 97, there are two round number present at tens places 90 and 100
STEP 2:
Out of 90 and 100, select the one which is nearest.
Hence for number 97, number 100 is the nearest and hence it is the best approximation for tens place
