We know that in the competitive exams, it is very important
to do calculation as fast as possible. For this we need short cut techniques.
So today I am going to tell you the fastest way to find square roots of the
numbers. Most of you already know this trick.
Square root is just a reverse of square...e.g. 52 = 25
so, sq. rt of 25 = 5
First of all, memorize the square table:
SQUARE TABLE
|
|
12 = 1
|
92 =
81
|
22 = 4
|
102 =
100
|
32 = 9
|
112 =
121
|
42 =
16
|
122 =
144
|
52 = 25
|
132 =
169
|
62 =
36
|
142 =
196
|
72 =
49
|
152 =
225
|
82 =
64
|
162 =
256
|
Look at the above table….Do you find any relation between the numbers and their squares? If not...Don’t worry chill...i will tell you...
Using above table we can made another table:
IF UNIT
DIGIT OF A NUMBER IS -
|
ITS SQUARE
ROOT WILL BE -
|
1
|
1 OR
9
|
4
|
2 OR
8
|
5
|
5
|
6
|
4 OR
6
|
9
|
3 OR
7
|
Now we can start-
See the picture, while reading each step:
1) Underline
2 digits from right side of the number:
Here we get 34 and 81.
2) Now see…, unit place of 81
is 1…
So from above chart we can say that,
Its square root will be 1 or 9.
3) Now read the square table from 1
to 7,
We can say that 34 comes between the squares of 5 and 6…since...
52 < 34 < 62
Now remember this, take always smaller number.
Now remember this, take always smaller number.
So between 5 and 6 …since, 5 is smaller , so our 1st digit of answer is 5.
4) From step 1 we get 34
and 81….
From step 2 we get 1 or 9…
From step 3 we get 5... Now multiply
this 5 with its consecutive no. (i.e.5+1=6)...
5×6 = 30
Now see… Is 34(from step 1) is greater or smaller than this 30?
Since... we know that 34 is greater than 30.
Therefore between 1 and 9, 9 is greater than 1…
So we should choose the greater no.
So, unit digit of our answer will be 9. (NOTE: If instead of 34 we had smaller no. than 30, then we would choose smaller no. between 1 and 9, i.e. 1 ,,
and suppose we had equal no. i.e, 30, thn we should choose biggr no. i.e, 9)
5) Therefore square root of 3481 is
59.
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