EASY MATHS TRICKS
(1) To find 2.5 percent of a number :
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* Choose a number: (start with 2 digits & advance to 3 later on).
* Divide by 4 (or divide twice by 2).
* Move the decimal point one place to the left.
EXAMPLE :
If the number selected is 110:
Divide 110 by 4: 110/4 = 27.5
Move the decimal point one place to the left : 2.75
So, 2.5% of 110 = 2.75.
(2) To find 5% of a number :
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*Choose a large number
* Move the decimal point one place to the left.
* Divide by 2 (take half of it).
EXAMPLE :
If the no. selected is 850:
Move the decimal point one place to the left: 85.0
Divide by 2: 85/2 = 42.50
So 5% of Rs.850 = Rs.42.50.
(3) To find 15% of a number :
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* Choose a 2-digit number.
* Multiply the number by 3.
* Divide by 2.
* Move the decimal point one place to the left.
EXAMPLE :
If the number selected is 43:
Multiply by 3: => 3 × 43 = 129
Divide it by 2: => 129/2 = 64.5
Move the decimal point one place to the left: 6.45
So 15% of 43 = 6.45
(4) To find 20 percent of a number:
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*Choose a 2-digit number.
* Divide the number by 5.
EXAMPLE :
If the number selected is 38:
Divide by 5: 38/5 = 7.6
So 20% of 38 = 7.6
(5) To find 25 percent of a number:
* Divide the no by 4.
EXAMPLE :
If the number selected is 86:
Divide 86 by 4: 86/4 = 21.5
So 25% of 86 = 21.5.
(6) To find 33 1/3 percent of a number :
* Choose a number.
* Divide the number by 3.
EXAMPLE :
If the number selected is 74
Divide by 3: 74/3 = 24 2/3
So 33 1/3% of 74 = 24 2/3
(7) To find 40 percent of a number :
* Choose a 2-digit number.
* Multiply the number by 4.
* Move the decimal point one place to the left.
EXAMPLE :
If the number selected is 21:
Multiply by 4: 4 × 21 = 84
Move the decimal point one place to the left: 8.4.
So 40% of 21 = 8.4.
(8) To find 45 percent of a number :
* Choose a 2-digit number.
* Multiply the number by 9.
* Divide by 2.
* Move the decimal point one place to the left.
EXAMPLE :
If the number selected is 36:
Multiply by 9: 9 × 36 = 324
Divide by 2: 324/2 = 162
Move the decimal point one place to the left: 16.2
So 45% of 36 = 16.2.
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