Short Tricks to find the Squares and Cubes of Numbers above 100

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One of the ardent follower of BankersAdda, Nitish shared with us a post on  “Short Tricks to find the Squares and Cubes of Numbers above 100“. So, here we are presenting to you the post by Nitish. Hope you like the post!!!



Hello my all BA friends. As all of you know that compound interest is one of the most important chapters  from which questions are always asked in PO, Clerk and also in SSC exams. So I am going to tell you some short tricks which will help you to find the answers in very less time. One more thing…once you understand the logic you will also be able to learn it and once you learn it, it become more time saving for you.


Squares of 110 to 116 – 


Well, I am not going to start it from 101 but from 110 because normally the interest rates are given in
the question from 10% to 15% or 16%. So try to understand it now –


As you know (A)
= P ( 1+ r/100)
t
 

So suppose (r) = 10% and (t) = 2 years then the value of ( 1+ r/100)t
          = (1+10/100)which gives (110/100)2


Now use trick to find the square of 110 –


(110)2 = 11x 100 = 12100 (this was easy… right) 

(111)2 = Add 11 to 111= 122 and now add square of 11(121) to the only last digit (digit on once place) of  122 i.e., in 2 which gives answer = 12321 

(112)2 = Add 12 to 112 = 124. Add square of 12(144) to the only last digit of 124 i.e. in 4 which gives = 12544 


(116)2 = Add 16 to 116 = 132. Now add square of 16(256) to the last digit of 132 i.e. in 2. Answer = 13456 

So the value of (116/100)2 = 1.3456


Now if you want to find Amount then just multiply principal with 1.3456 and if it is asked only Compound Interest then just multiply the principal with 0.3456.


Hope you have cracked the trick now….if yes then it’ll be good for you to learn it!!


Cubes of 101 to 115 – 
This one will help you when the TIME is given for 3 years i.e., (A) = (1+r/100)3


(101)=1030301. (Remember in cubes of 101 to 115 the answer will be always in seven digits numbers.)


You can find this answer in three small steps –
1. Multiply 3 in only last digit of 101 i.e. in 1. It gives 103


2. Multiply 03 ( from 103) in last digit of 101 i.e. in 1 again, it gives 03. Write it after the first step answer like-10303 


3. Now you got 5 digits and only two digits are left. In this last step write the cube of last digit of 101 which gives 1 and add 0 before it i.e. 01 and write it after the second step answer i.e. 1030301. This is your answer.


(102) = 102 x 3 (in just last digit) =106.
             06 x 2 = 12 = 10612
             Cube of 2 = 8 i.e. 08 = 1061208 (answer)


(103)= 103 x 3 = 109
             09 x 3 = 27 = 10927
             (3)= 27 = 1092727 (answer)


(104)3  = 104 x 3 = 112

            12 x 4 = 48 = 11248
            (4)= 64 = 1124864 (answer)


(105) = 105 x 3 = 115

             15 x 5 = 75 = 11575
             (5)= 125 = 1157625 ( add 1 of 125 to just last digit of 11575)


(106)3  = 106 x 3 = 118

            18 x 6 = 108. Now add 1 of 108 to the last digit of 118, it gives 11908
            (6)3 = 216. Add 2 of 216 to the last digit of 11908, it gives 1191016(answer)


(109)3  = 109 x 3 = 127

            27 x 9 = 243. Add 2 of 243 to last digit of 127 = 12943
            (9)= 729. Add 7 of 729 to the last digit of 12943 = 1295029(answer)


(111)3  = 111 x 3 = 133

             33 x 11 = 363. Add 3 from 363 in last digit of 133 = 13663
            (11)= 1331.


As you already got 5 digits so you need only 2 digits but you have 4 digits in your hand i.e. 1331 so now add 13 from 1331 to the last two digits of 13663 and it gives 1367631(answer).


(115)3 = 115 x 3 = 145

             45 x 15 = 675. Add 6 from 675 to the last digit of 145 = 15175
             (15)= 3375. Add 33 from 3375 to the last two digit of 15175 = 1520875 (answer)


So the value of (115/100)3 = 1.520875.


Follow the same rule to find the Amount and Compound Interest as I told earlier. Multiply 1.520875 with principal to find Amount and multiply 0.520875 to find only Interest.


That’s all friends. I know cube tricks are looking tough but believe me once you catch it, it become easy to learn. These tricks will also help you in questions of Simplification.


THANK YOU!!!


— Nitish Chakraborty