Aptitude Test Maths

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Quick Math:

Learn the following fractions and you will be able to solve quick math problems without calculator.

1/3=0.3333

2/3=0.6666 ( See Example Q below)

1/4=0.25

2/4=0.5

3/4=0.75

1/5=0.2
2/5=0.4
3/5=0.6
4/5=0.8

1/6=0.1666
2/6=0.3333
3/6=0.5
4/6=0.6666
5/6=0.8333

1/7=0.1428
2/7=0.2857
3/7=0.4285
4/7=0.5714
5/7=0.7142
6/7=0.8571

1/8=0.125
2/8=0.25
3/8=0.375
4/8=0.5
5/8=0.625
6/8=0.75
7/8=0.875

1/9=0.1111
2/9=0.2222
3/9=0.3333
4/9=0.4444
5/9=0.5555
6/9=0.6666
7/9=0.7777
8/9=0.8888

You have to rote-memorize these fractions to be able to solve quick-math problems.

Example Q: 9 X 0.6666 = ?

A= 7.3636
B= 6
C= 8.4224
D= 6.6

Solution: 9 X 0.6666= 9 X 2/3 = 6

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Q. Increase:

60 by 35%
60 X 135/100 = 81

28 by 125%
28 X 225/100 = 63

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Q. Decrease:

32 by 25%
=32 X (100-25)/100
=32 X 75/100
=24

216 by 37.5%
=216 X (100-37.5)/100
=216 X 62.5/100
=135

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Q. What number when increase by 15% becomes 161?

Let a be the required number

a X 115/100 = 161

a= 161 X 100/115

a= 140

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Math Shortcuts:

When Multiplying a number by 5:

68 X 5 = ?
=68 X 5
=68 X 10/2
=680/2
=340

When dividing a number by 5:

260/5 = ?

=260/10 X 2

=26X2

=52

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Take the original number and imagine a space between the two digits

Q. 52 X 11

5_2
Now add the two numbers together and put them in the middle:
5_(5+2)_2
=572

If the numbers in the middle add up to a 2 digit number, just insert the second number and add 1 to the first:

9_(9+9)_9

9_(18)_9
(9+1)_8_9
10_8_9
=1089

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Quick Square:

If you need to square a 2 digit number ending in 5, you can do so very easily with this trick. Mulitply the first digit by itself + 1, and put 25 on the end.

Q. 25^2

= 25^2

= _25

= 2(2+1)_25

= 2(3)_25

= 625

Q. 35^2

= 35^2

= _25

= 3(3+1)_25

=3(4)_25

=1225

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Tough Multiplication:

If you have a large number to multiply and one of the numbers is even, you can easily subdivide to get to the answer:

32 X 125 = ?

32 x 125, is the same as:

16 x 250 is the same as:

8 x 500 is the same as:

4 x 1000 = 4,000

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Problem Solving:

Q- The workers of an electronic company were given an increase of 8% of their monthly salaries. If Mr. Leoni Messi earned $600 per month originally, find his salary after the increment.

Solution:

=600 X 108/100

=648

Mr. Leoni Messi's salary after increment is 864. Find his orginal salary.

Solution:

= 864 X 100/108

= 800

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Q. A man invests 40% of his savings in the stock market. He invests 50% of the remainder in property and deposits the remaining balance in a bank's savings account. If this last amount is $15000, what was his total savings?

Solution:

40% in Stock Market. Remainder is 60%.

50% of the remainder (60%) is 30% which he invested in property. The remaining 30% is $15000.

30%=15000

1%= 15000/30

1%= 500

100%= $50000

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