Question

the sum of number when a number is increased by 10% and decreased by 10% is 100 what is the number

Answer 1

Solution :-

Let the required number be 100.

Then, according to the question.

⇒ Firstly, the number is increased by 10 %

⇒ 100 + (100*10)/100

⇒ 100 + 10

= 110

Secondly, it is decreased by 10 % 

⇒ 110 - (110*10)/100

⇒ 110 - 11

⇒ 99

Net increase or decrease percentage

= (Original Number - New Number)*100/100

⇒ (100 - 99)*100/100

⇒ (1*100)/100

⇒ 100/100

= 1 %

So, net decrease is 1 %.

Answer 2

let the number be 'x '

increased number = x + 10% of x

x + 0.1x = 1.1 x

decreased number = x - 10% of x

= x - 0.1x = 0.9x

sum = 100

1.1x + 0.9x = 100

2x = 100 => x = 50

Answer: required number = 50