Tuesday 26 February 2013

SQUARE ROOT

Finding square root of any number..

before starting you have to remember this square chart..... look for the last digit of the square....
1 = 1
2 = 4
3 = 9
4 = 6 (16)
5 = 5 (25)
6 = 6 (36)
7 = 9 (49)
8 = 4 (64)
9 = 1 (81)

now all we have have to do is to apply the rule as applied in finding the cube roots CLICK HERE TO KNOW

lets take an example..
eg.  find square root of 3481

step1 divide number in group of two starting from the back .....   34   and 81
 
step2.  look at the it shows that 1 comes for 9 and 1 both in the last. therefore either root will end with 1 or 9

step3. now we are left with 34 ... square of 5 is 25 which is less than 34 but square of 6 is 36 which is more ...... therefore our answer sud be either 51 or 59...

Now to get the correct answer you must know how to find square of any number ending with 5...
if not then here it is...
square of 25= 625 ( write 25 at the and then multiply the number left with the next higher number)
                   = 2 X 3 ( higher number)= 6
another example 65= 4225
                              = 6 X 7 ( higher number) 42 and write 25 after this= 4225

Lets get back to our chart once again.. you will see that last number repeats itself after crossing the square of 5....

1 and 9 = 1
2 and 8 = 4
3 and 7 = 9
4 and 6 = 6

now square root of 3481 can either be 51 or 59 as explained above...
to know the correct answer simply find the square of 55 ( lies in between 51 and 59) = 3025....
now as  3481 is greater than 3025 therefore 59 is the square root of 3481.....



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8 comments:

  1. Hi Dedo,
    Nice explanation.
    Can you please explain how to solve square root more than 4 digits. Ex. 1471369 and for decimal fraction i.e 175.2976

    ReplyDelete
  2. the same technique will be used but as digit increase the number of step required to solve also increases therefore its betr to take the first and the last digit by using the technique and then work out with the options.....
    for eg in your question the first an last digit of the answer will 1... 3 or 7
    the same rule works in decimal also

    ReplyDelete
    Replies
    1. 3481
      1)take 34 its in between square of 5-6
      2)now take last digit(1),1 comes for squares of 1,9
      3)dought in between 51,59
      4)our first 2 digits is 34 nearer squares are 5,6 now take 5*6=30
      34 is more than 30 so answer is 59
      if first two digitts 27 or 28 or 29 then it will lie beyween 51-54

      Delete
  3. I GOT IBPS CLERK-II SCORE AFTER INTERVIEW 64.60% . I AM GEN CATEGORY NOW WHAT IS MY POSITION . WHAT WILL BE EXPECTED CUT OFF SCORE FOR GEN IN MP IBPS CLERK-II.

    ReplyDelete
  4. but how to find out the square root of numbers like 1792 or 2453 (bcoz for digits ending with 2,3,7 u have not mention anything in ur chart)...... I am even confused to find out the square root of 3 digit numbers or 5 digit numbers.......... plz help DODO......

    ReplyDelete
    Replies
    1. number ending wid 2,3 and 7 dnt have perfect square.....
      u can use the same method for 3 digit also

      Delete
  5. Plz explain square root of 84111

    ReplyDelete