Fast and Easy Method to Take Square
Root- Math Tricks:
Fast and Easy Method to Take Square
Root is given here, candidates those who are preparing for banking and all
other competitive exams can use this trick in the examination to save time.
POINTS TO REMEMBER:
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When 22 = 4, then √4 = 2 ·
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Here 4 is the square of 2 ·
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2 is the square root of 4 ·
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A Square of a number can never end
with 2, 3, 7 and 8
Table 1:
One’s digit of a square One’s digit of the square root
1 1 or 9
4 2 or 8
5 5
6 4 or 6
9 7 or 3
To find the square of a number
which is a multiple of ‘5’
252 = [2×3] 52 = [6] 25 = 625
i.e., AB2 where B=5
AB2 = [A× next
number] B2
For example, 852 =
[8×9] 25 = 7225
1152 = [11×12] 25 =
13225
1552 = [15×16] 25 = 24025
This method can be followed for all numbers divisible by 5
TYPE 1: To find the square root of a 3-digit number EXAMPLE: √841 S
STEP 1: Consider the one’s digit of the given number i.e., 1
From Table 1, if the one’s digit of the square is ‘1’ then the square
root would either end with ‘1’ or ‘9’
STEP 2: Always ignore the ten’s digit of the given number STEP 3: Now
the remaining number other than the one’s and the ten’s digit in the given
number is ‘8’
Consider a square-root of a square which is nearer to as well as lesser
than ‘8’.
Here it is ‘4’ which is nearer to as well as lesser than ‘8’. Hence the
square root of 4 i.e., ‘2’ is taken
STEP 4: we already know the one’s digit of the square root to be either
1 or 9 from STEP 1
Therefore the square root of ‘841’ lies between 21 and 29
STEP 5: Take a number divisible by ‘5’ between 21 and 29, that is ‘25’
252 = [2×3] 25 = 625
Now 625 < 841 252 is itself lesser than 841. Then 212 will be
much lesser than 841.
Therefore, the remaining option is ‘29’ √841 = 29
TYPE 2: To find the square root of a 4-digit number EXAMPLE: √8464
STEP 1: Consider the one’s digit of the given number i.e., 4 From Table
1, if the one’s digit of the square is ‘4’ then the square root would either
end with ‘2’ or ‘8’
STEP 2: Always ignore the ten’s digit of the given number
STEP 3: Now the remaining numbers other than the one’s and the ten’s
digit in the given number is‘84’ Consider a square-root of a square which is
nearer to as well as lesser than ‘84’. Here it is ‘81’ which is nearer to as
well as lesser than ‘84’. Hence the square root of 81 i.e., ‘9’ is taken
STEP 4: we already know the
one’s digit of the square root to be either 2 or 8 fromSTEP 1
Therefore the square root of ‘8464’ lies between 92 and 98
STEP 5: Take a number divisible
by ‘5’ between 92 and 98, that is ‘95’
952 = [9×10] 25 =
9025
Now 9025 > 8464 952 is itself
greater than 8464.
Then 982 will be much greater than 8464 Therefore, the remaining option
is ‘92’ √8464 = 92
TYPE 4: To find the square root of a 5-digit number EXAMPLE: √18769
STEP 1: Consider the one’s digit of the given number i.e., 9 From
Table 1, if the one’s digit of the square is ‘9’ then the square root
would either end with ‘3’ or ‘7’ STEP 2: Always ignore the ten’s digit of the
given number
STEP 3: Now the remaining numbers other than the one’s and the ten’s
digit in the given number is‘187’ Consider a square-root of a square which is
nearer to as well as lesser than ‘187’ Here it is ‘169’ which is nearer to as
well as lesser than 187. Hence the square root of 169 i.e., ‘13’ is taken
STEP 4: we already know the one’s digit of the square root to be either
3 or 7 from STEP 1
Therefore the square root of ‘18769’ lies between 133 and 137
STEP 5: Take a number divisible by ‘5’ between 133 and 137, that is
‘135’
1352 = [13×14] 25 = 18225
Now 18225 < 18769
1352 is itself smaller than 18769. Then 1332 will
be much lesser than 18769
Therefore, the remaining option is ‘137’
√18769 = 137