Question

A number is increased by 10% and then decreased by 10% . Find net increase or decrease per cent.

Answer 1

let 1st no. be x
increase by 10%
x+x/10=11x/10
now decrease 10%
11x/10-(11x/10)/10=99x/100
the decrease is x-99x/100
x/100
decrease % is 1%

Answer 2

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.