QUANT CONCEPTS + QUIZ #11

SQUARE OF NUMBERS

Some shortcuts:

Finding Square of a number which lies between 25-50

E.g.: Find the square of 43

1. Find how far the number i.e. 43 is from 50 → 7

2. Square the number. The result will be the last two digits of the required solution i.e. 7 square = 49.

3. Subtract 25 from the original number (i.e. 43) → 43-25 = 18

4. The final answer is 1849

Finding Square of a number which lies between 51-75

E.g.: Find the square of 53

1. Find how far the number i.e. 53 is from 50 → 3

2. Square the number. The result will be the last two digits of the required solution i.e. 3 square = 09.

3. Subtract 25 from the original number (i.e. 52) → 53-25 = 28

4. The final answer is 2809

Finding Square of a number which lies between 75-100

E.g.: Find the square of 93

1. Find how far the number i.e. 93 is from 100 → 7

2. 93-07 = 86. This forms the left hand part of the answer.

3. The square of the deficiency is 7 square = 49. This forms the right hand part of the answer.

4. The final answer is 8649

Finding Square of a number which lies between 100-125

E.g.: Find the square of 103

1. The surplus is 3. So add 3 to the actual number, 103 + 3 = 106. This gives the left hand part of the answer.

2. Square the surplus is 3 square = 09.

3. The final answer is 10609.

Now try to solve these 10 questions as fast as possible (3-5 min)

1.    Find the square of 44?

           (a)  1536                            (b) 1936

           (c) 1816                            (d) 2016

2.    Find the square of 12.3.

            (a)  155.09                         (b) 149.39

            (c) 151.29                         (d) 147.09       

3.    Find the square of (187-51)

            (a)  18166                          (b) 18496

            (c) 18266                          (d) 18096

4.    Find the square of (17/21).

           (a)  189/441                       (b) 289/441 

           (c) 189/481                       (d) 183/481

5.    Find the difference between the squares of 82 and 21.

           (a)  6283                            (b) 6371

           (c) 6171                            (d) 6271

6.    Find the square of 155.

           (a)  24655                          (b) 24475

           (c) 25625                          (d) 24025

7.    Find the square of 99999?

           (a)  9999800001                (b) 9999980001

           (c) 99998800001              (d) 9998880001

8.    Find the square of 125.

           (a)  16525                           (b) 15525

           (c) 15625                           (d) 16625

9.    Find the square of 8.9

(a)  79.21                           (b) 65.81

(c) 77.81                            (d) 64.81

10.  Find the square of 1405?

            (a)  1960225                      (b) 1974025

            (c) 1962025                      (d) 1971525

SOLUTIONS

Q	Ans	Q	Ans
1	b	6	d
2	c	7	a
3	b	8	c
4	b	9	a
5	a	10	b

Time taken

Within 3 min: EXCELLENT

3-5 min: YOU CAN DO BETTER

More than 5 min: YOU NEED TO WORK HARD