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Percentage Increase or Decrease Using Multiplier

Percentages - Concepts

Ratio and Percentages

Using OF Operator in Percentages

Express the Fraction as Percentage

Express Decimal as Percentage

Express as Percentage

Percentage Change

Percentage Increase or Decrease Using Multiplier

Percetage Increase or Decrease

Unitary Method In Percentages

Class - Clerk-cum-Cashier Subjects

Concept Explanation

Percentage Increase or Decrease Using Multiplier

To calculate percentage increases and decreases, we use Percentage multipliers. Percentage multipliers allow us to calculate percentage increases and percentage decreases very quickly with one single multiplication.

To increase an amount by 15% we start with 100% of the amount, then add 15% of the amount to it. We now have 100% + 15% = 115% of the amount.

So, to increase an amount by 15% in one step. we multiply the amount by 115% or 1.15. The value 1.15 is called the multiplier.

To decrease an amount by 15%, we start with 100 of the amount, then subtract 15% of the amount from it. We now have 100% - 15% = 85% of the amount.

So, to decrease an amount by 15% in one step. we multiply the amount by 85% or 0.85. The value 0.85 is called the multiplier.

Illustration 1: Evaluate the following:

(a) Increase 312 kg by 22%, giving your answer to 3 significant figures.

(b) Decrease Rs183 by 7%.

Solution :

(a) To increase by 22%, we multiply by 100% + 22% = 122%, which is 1.22. Hence, 1.22 is the multiplier.

$therefore$ the new amount = 1.22 $times$ 312 kg = 380.64 kg $approx$ 381 kg

(b) To decrease by 7%, we multiply by 100% - 7% = 93%, which is 0.93.

$therefore$ the new amount = 0.93 $times$ Rs 183 = Rs 170.19 = Rs 170

Illustration 2: Find the multiplier corresponding to an increase of 25%?

Solution: To increase an amount by 25% we start with 100% of the amount, then add 25% of the amount to it. We now have 100% + 25% = 125% of the amount.

So, to increase an amount by 25% in one step. we multiply the amount by 125% or 1.25. The value 1.25 is called the multiplier.

Illustration 3: The school fee of Jack increased by 30%. His last year school fee was Rs 2500 per month. Find the amount which Jack has to pay this year every month?

Solution: Original school fee of Jack = Rs 2500

Increase in fee this year = 30 %

So, now he has to pay = 2500 X multiplier

To increase an amount by 30% we start with 100% of the amount, then add 30% of the amount to it. We now have 100% + 30% = 130% of the amount.

So, to increase an amount by 30% in one step. we multiply the amount by 130% or 1.30. The value 1.30 is called the multiplier.

$therefore$ the new amount = 1.30 X Rs 2500 = Rs. 3250

So, Jack has to pay Rs 3250 this year every month.

Sample Questions

(More Questions for each concept available in Login)

Question : 1

A price rose from $5 to $7. What percent increase is this?
A. 40%	B. - 40%	C. 45%	D. 20%
Right Option : A
View Explanation

Question : 2

Find the multiplier corresponding to a decrease of 19%
A. 0.89	B. 0.56	C. 0.88	D. 0.87
Right Option : A
View Explanation

Question : 3

The population of a small town decreased from 18,560 to 15,787 due to breakout of an epidemic. What is the percentage decrease in the population?
A. 14.94%	B. 14.74%	C. 13.94%	D. -14.94%
Right Option : A
View Explanation