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Maths Tricks for Bank Exams

Maths Tricks for Bank Exams:

Basic Tips to speed up the calculations in Bank Exams:

Before going to start our preparation for bank exams. First of all, we have to memorize some basic things in maths.
Speed Maths Tricks

We have to memorize 20 multiplication tables completely in such a way that we can able to tell without thinking.

  • Learn Squares of numbers up to 30(22,32,…..302).

  • Cubes of numbers up to 20(23,33………203).

  • Powers of 2 ( 22 , 23 , 24 ……28).

  • Powers of 3 – 32 , 33 , 34 35

  • Memorize some factorial values up to 10!.

  • Fractional values 1/2, 1/3, 1/4 ….. up to 1/20.

Shortcut Tips To Solve Quantitative Aptitude in Less Time: (Speed Maths Tricks)




TOPICS:

  • Squares & Square Roots

  • Cubes & Cube Roots

  • Multiplication

  • Division

  • Addition

  • Subtraction

  • Simplification Tricks Using Formulae

  • Fractions: Tips to find Smaller & Larger

  • Useful Conversions

  • Averages

  • Percentages

  • Miscellaneous

SQUARES:

Squaring Tricks: Find squares of numbers in Using Smart Ways:

I. Squaring of 2 digit numbers which begin with 5.

Example:

  1. (51)2 = (52 + 1), (01) 2 è [1st two digits, 2nd two digits].

= 2601.

  1. (56)2 = (52 + 6), (62)

= 3136.

  1. (58)2 = 52 + 8 , 82

= 3364.

  1. (59)2 = 52 + 9 , 92

= 3481.

II. Squaring numbers which are near to 100. ( i.e. 80 to 130)

Examples:

  • (86)2 = 1st part /2nd part

= (86 -14) / 142

= 72 1 96 = 7396.

  • (89)2 = (89-11) / (11)2

= 78 1 21 = 7921

  • (97)2 = 97-3 / 32

= 9409

  • (99)2 = (99-1) / 12

=9801

  • (106)2 =1st part / 2nd part

= (106 +6) / 62

= 11236

  • (107)2 = (107 + 7) / 72

= 11449.

  • (112)2 = 112+12 / 122

= (124) / 1 44

= 12544.

 

  • (119)2 = (119 +19) / 192

= 138 / 361

= 14161.

III. Squaring the numbers which are near to 1000.

Examples:

  1. (990)2 = 1st 3 digits/ 2nd 3 digits

= (990 -10) /102

= 980100.

2. (992)2 = (990 -8) / 82

= 982064.

3. 1006 = 1006 +6 /62

= 1012036.

Multiplication:




Multiplication Tricks:

Learn some multiplication techniques .Here I am providing below.

      1. Multiplying the two digit numbers which are having the same number in tens place to and ending with 5.

Eg: 1) 25 * 25 = (2*3)25=625

2) 35 * 35 = (3*4)25=1225

3) 65 * 65 = (6*7)25=4225

      1. Multiplying 2 digit numbers ending with 5 and also their difference should be 10.

Eg:- 1) 15 * 25 = (1*3)75 = 375.

2) 35 * 45 = (3*5)75 = 1575.

3) 25 * 35 = (2*4)75 = 875.

      1. Multiplying the two digit numbers having the same number in the tens place and the addition of unit digits should be 10.

Eg:- 1) 23 * 27= (2*3) 21= 621.

2) 24 * 26 = (2*3) 24= 624.

3) 36 * 34 = (3*4)24 = 1224.

100-93=7 , 100-92=8. Smallest of 8 and 7 can be deducted from smaller number of 92 and 93.Here we take 92-7 .
      • Multiplying the two digit numbers having 9 in the tens place and different numbers in unit place.
      • Eg:- 1)92*93=(92-7)(8*7)=8556

2)93*97=(93-3)(7*3)=9021

Already we remember squares of two digit numbers up to 30. Then we follow the below methods to find the squares of numbers from 30 to 80.

      • Here we take the base number as 50 and then split the given number.
( if we want to find square of 39 it can split to 50-11 )

502=2500, 112=121

 

Eg: 392= (50-11)

      • 2500

1100 (-)

1400

121 (+)

1521

If we practice then these calculations we can do mentally without using paper .I will explain with one more example.

Eg 2:- 632= 50+13

      • 2500

1300 (+)

3800

169 (+)

3969

Squaring numbers from 90 to 99.

Here, 100-94 = 6

Eg: 1) 942=(94-6)62

= 8836

Here, 100-96 = 4

2)962=(96-4)42

= 9216.

Addition :

The method of adding is very simple and everyone can do this. But, the thing is adding numbers in shortest possible time is important.

I.Single Column Addition:

For Example: Add below numbers from bottom to top by following simple technique.

  • 9
  • 7
  • 8
  • 5
  • 4
  • 7
  • 6

while adding the above numbers from bottom to top. Don’t say 6 plus 7 is equal to 13 and 13 plus 4 is equal to 17 and 17 plus 5 is equal to 22 and so on. It is too time-consuming. Here, we have to use strategy saying like this. 6 then 13, 17,22, 30 and so on and do mind calculations and don’t require to say out each and everything its very time taking.

II. Double Column Addition:

Double column addition is absolutely useful for quick calculations in competitive exams.
Example :
89
56
23
78
45
12
The addition of numbers starting from bottom starts as 12 +40(of 45) and then giving 57, 57+70( of 78) and then giving 135 and so on.
III. Addition of Multiple column Numbers:
Example :
58964
45896
52639
78954

Here, First start adding double columns each time. It takes less time compared to the normal method. Once the 1st set of double column(units and tens place digit numbers ) is mastered. It becomes easy to add the 2nd set of double column i.e. 100’s place and 1000’s place digits.

Subtraction:

Solving questions without using pen and getting answers mentally saves much time in bank exams. Here, we are providing some subtraction shortcut methods which are useful in solving DI problems and also simplifications in bank exams.

Suppose, if we need to subtract 66 from 92. Mentally increase the number to the nearest multiple of 10 that means to increase 66 to 70 by adding 4 and at the same time mentally increase the number to the nearest multiple of 10 i.e. increase 66 to 70 by adding 4 and at the same time, increase the other quantity by the same amount i.e. by 4 then 92 becomes 96.

Therefore, the problem now is 96 minus 70 with this we can get instant answers mentally without using pen i.e. 26.

Eg: 3 5 8
-2 6 7 5
+6 5 8 8
-3 5 6 9
2 7 0 2
Generally, we find questions as below or these type of calculations are much useful in solving data interpretation problems in bank exams.

Q.1) 358 – 2675 +6588 -3569 =?

If we try to solve in double column wise. Sometimes, we no need to solve entire answer by knowing the answer of last two digits from the options we can able to checkout correct answer.

Simplification Methods:

In some simplification problems may sometimes involves application of algebraic formulae listed below:

  1. (a+b)2 = a2 + 2ab + b2
  2. (a +b)2 = a2 – 2ab + b2
  3. (a+b)3 = a3 +3ab (a+b) +b3
  4. (a-b)3 = a3 – 3ab (a+b) – b3
  5. (a2 –b2) = (a+b)(a-b)
  6. (a3+ b3) = (a+b)(a2-ab+b2)
  7. (a3– b3) = (a-b)(a2+ab+b2)

Tips to Solve Fractions -Ascending/Descending Order :

In some cases, we find comparision of fractions in bank test papers.

It’s time-consuming if we do by calculating the decimal value and compare. But the simple technique to do in seconds is comparing by doing cross multiplication of two fractions .whichever is the big number after cross multiplying that fraction is big as vice-versa.

For example:

Compare, 3/4 and 1/4.

By seeing itself, we can say 3/4 is big. Implement here our logic of cross multiplication of two fractions.

¾ ¼ we get, 12 and 4 we know 12 > 4 so we can say ¾ >1/4

Apply the same logic big fractions it’s very simple and takes less time.

Problem 1: Arrange the following fractions in ascending order.

5/6, 3/4, 2/9, 1/5

Sol: Ascending->Arise ( go up)( small to big)

Descending-> down( big to small)

Here compare the cross multiplication values whichever is smaller that fraction is the small one.

1442205095257

We have compared remaining fractions 3/4 and 5/6 as same as above process.

Finally, we get, 1/5 <2/9 <3/4 <5/6.

If we understand the logic behind this and practice 3 problems it will take less time without paper.

Some of the useful conversion factors:

  1. 1foot = 12 inches =30.48 milimetres
  2. 1 inch = 2.54 centimetres = 25.4 millimetres
  3. 1 mile = 1.609 kilometres
  4. 1 acre = 4000 sq.metres = 43560 sq. fts
  5. 1 quintal = 100 kgs
  6. 1 hectare = 2.5 acres = 10000 sq. metres
  7. 1 Metric Ton = 1000 kgs
  8. 1kg = 2.204 pounds
  9. 1 gallon = 4.5 litres
  10. 1 degree = 12 inches = 60minutes

 

Divisibility :

When we do division of big numbers. we cant know whether it is divisible or not. For this to find before, Here are some rules for testing divisibility of a number by 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12.

A Number is divisible byIF
2The last digit is 0,2,4 6 or 8 ( any even number)
3The sum of all digits is divisible by 3
4The last 2 digits form a number divisible by 4 or 00.
5The last digit is either 0 or 5.
6It is divisible by both 2 and 3.
8The last 3 digits form a number divisible by 8 or 000.
9The sum of all digits is divisible by 9.
10The last digit is 0.
11The difference between the sum of digits at odd and even places is either 0 or in multiples of 11.
12It is divisible by both 3 and 4.




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