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1.For
faster calculations
1. The first requirement is to mug up tables till 30, reciprocals
with respect to percentage and decimals, squares & cubes till 30,
square roots and cube roots till 7.
2. Practice various questions to become comfortable with the
various types of problems and understand by which method you can solve a
particular problem faster. Exposure to various types of questions is
required so CAT does not come as a surprise to you.
3. Be very thorough with basics of all arithmetic topics like
profit, loss and discount, ratios, basic number theory and formulas.
4. Take sectional tests and analyse your performance. This helps
you to understand your strengths and weaknesses. Remember, a test is not
conducted to tell you that you perform at 80% efficiency but to point out
the 20% area where you are making mistakes.
5. Try vedic maths and learn short-cut methods that work for you.
Also, try doing mental calculations and minimise the use of using pen and
paper.
6. Approximation is the best tool to arrive at answers quickly but
using it is an art, you will have to learn this through trial-and-error
and practice.
7. Often you can arrive at the correct answer by the process of
elimination. For some questions you may see that two or three of the given
options are pretty far fetched and it is easy to select the right answer.
Again, this method needs practice to perfect.
8. Whenever you try to calculate faster then your comfort zone
speed, you are bound to make silly mistakes. So, try to build up your
speed slowly so that it peaks in November when all the entrance tests are
about to begin.
2.The
Importance Of Reciprocal Percentages And Fractions
The
CAT tests your ability to interpret and understand questions based on
facts and figures. To tackle the QA & DI sections, you need to have a
good understanding of number theory. Lets take an example.
Suppose
you are to calculate 5.26% of 760 as a sub-step of a DI calculation say
something like
(526/200) X (760/100) => {(5.26/100) X (760/1)} 1/20
You should know the equivalent fraction of 5.76% (It is actually 1/19 ),
it reduces to (40) X 1/20 = 2
This
can save you vital 15 – 20 seconds (at least) and saving this much time
in almost every question means a higher attempt and higher accuracy.
So,
be sure to spend time learning equivalent fraction & percentages from
1/1 to 1/30.
Here
are some tables to help you out…
|
Number
|
Reciprocal
|
Decimal
|
Percentage
|
|
1
|
1/1
|
1.0
|
100
|
|
2
|
1/2
|
0.5
|
50
|
|
3
|
1/3
|
0.33
|
33.33
|
|
4
|
1/4
|
0.25
|
25
|
|
5
|
1/5
|
0.20
|
20
|
|
6
|
1/6
|
0.166
|
16.66
|
|
7
|
1/7
|
0.142
|
14.28
|
|
8
|
1/8
|
0.125
|
12.50
|
|
9
|
1/9
|
0.1111
|
11.11
|
|
10
|
1/10
|
0.1
|
10
|
3. Tips To Remember Some Values
The
values of reciprocal percentages (RP) for 6 is exactly half that for 3
(half of 33.33 = 16.66)
The
RP for 8 is exactly half of 4 (half of 25 = 12.5)
Seven
is easy to remember just 7 into 2 (14), followed by 14 into 2 (28) which
makes it 14.28
9
is one-third of 3 (33.33 divided by 3 = 11.11)
Please
start with the next ten only after becoming absolutely comfortable with
the first ten
|
Number
|
Reciprocal
|
Decimal
|
Percentage
|
|
11
|
1/11
|
0.09090
|
9.09
|
|
12
|
1/12
|
0.0833
|
8.33
|
|
13
|
1/13
|
0.077
|
7.7
|
|
14
|
1/14
|
0.0714
|
7.14
|
|
15
|
1/15
|
0.0666
|
6.66
|
|
16
|
1/16
|
0.0625
|
6.25
|
|
17
|
1/17
|
0.0588
|
5.88
|
|
18
|
1/18
|
0.0555
|
5.55
|
|
19
|
1/19
|
0.0526
|
5.26
|
|
20
|
1/20
|
0.05
|
5
|
By
now you would have figured out that the difficult ones are the prime
numbers. We have already dealt with 7. Now we need to work out 11, 13, 17,
19, 23 and 29.
9
and 11 are interrelated as 1/9 is 11.11 and 1/11 is 9.09
13 is considered unlucky. The way you remember it is through the year
1977,which proved unlucky for Indira Gandhi and Coca Cola.
All
even numbers can be worked out by dividing the RP for the number that was
their half or quarter by two or four respectively. For example, 12 is half
of 6 (half of 16.66 = 8.33)
Workout the rest of the primes and your own unique way to remember them.
We cannot emphasize the importance of having the percentages of the 1st 30
reciprocals on your fingertips.
|
Number
|
Reciprocal
|
Decimal
|
Percentage
|
|
21
|
1/21
|
0.0476
|
4.76
|
|
22
|
1/22
|
0.04545
|
4.54
|
|
23
|
1/23
|
0.0434
|
4.34
|
|
24
|
1/24
|
0.0416
|
4.16
|
|
25
|
1/25
|
0.04
|
4
|
|
26
|
1/26
|
0.0384
|
3.84
|
|
27
|
1/27
|
0.0370
|
3.7
|
|
28
|
1/28
|
0.0357
|
3.57
|
|
29
|
1/29
|
0.0344
|
3.44
|
|
30
|
1/30
|
0.0333
|
3.
|
4. Composite Table
|
Sl.No
|
RV
|
%
RV
|
Square
|
Cube
|
Fourth
term
|
Square
Root
|
Cube
Root
|
|
1
|
1.00
|
100
|
1
|
1
|
1
|
1.00
|
1
|
|
2
|
0.50
|
50.00
|
4
|
8
|
16
|
1.41
|
1.25
|
|
3
|
0.33
|
33.33
|
9
|
27
|
81
|
1.73
|
1.44
|
|
4
|
0.25
|
25.00
|
16
|
64
|
256
|
2.00
|
1.58
|
|
5
|
0.20
|
20.00
|
25
|
125
|
625
|
2.24
|
1.70
|
|
6
|
0.17
|
16.67
|
36
|
216
|
1296
|
2.45
|
1.81
|
|
7
|
0.14
|
14.29
|
49
|
343
|
2401
|
2.65
|
1.91
|
|
8
|
0.13
|
12.50
|
64
|
512
|
4096
|
2.83
|
2
|
|
9
|
0.11
|
11.11
|
81
|
729
|
6561
|
3.00
|
2.08
|
|
10
|
0.10
|
10.00
|
100
|
1000
|
10000
|
3.16
|
2.15
|
|
11
|
0.09
|
9.09
|
121
|
1331
|
|
|
|
|
12
|
0.08
|
8.33
|
144
|
1728
|
|
|
|
|
13
|
0.08
|
7.69
|
169
|
2197
|
|
|
|
|
14
|
0.07
|
7.14
|
196
|
2744
|
|
|
|
|
15
|
0.07
|
6.67
|
225
|
3375
|
|
|
|
|
16
|
0.06
|
6.25
|
256
|
4096
|
|
|
|
|
17
|
0.06
|
5.88
|
289
|
4913
|
|
|
|
|
18
|
0.06
|
5.56
|
324
|
5832
|
|
|
|
|
19
|
0.05
|
5.26
|
361
|
6859
|
|
|
|
|
20
|
0.05
|
5.00
|
400
|
8000
|
|
|
|
|
21
|
0.05
|
4.76
|
441
|
9261
|
|
|
|
|
22
|
0.05
|
4.55
|
484
|
10648
|
|
|
|
|
23
|
0.4
|
4.35
|
529
|
12167
|
|
|
|
|
24
|
0.04
|
4.17
|
576
|
13824
|
|
|
|
|
25
|
0.04
|
4.00
|
625
|
15625
|
|
|
|
|
26
|
0.04
|
3.85
|
676
|
17576
|
|
|
|
|
27
|
0.04
|
3.70
|
729
|
19683
|
|
|
|
|
28
|
0.04
|
3.57
|
784
|
21952
|
|
|
|
|
29
|
0.03
|
3.45
|
841
|
24389
|
|
|
|
|
30
|
0.03
|
3.33
|
900
|
27000
|
|
|
|
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