Question

a number is increased by 10% and then it is decreased by 10% find the net increase or decrease percent

Answer 1

,
Assume the  number to be 100 for instance, 
10% of 100 increased = 100 + ( 10/100*100 )
= 100 + 10 = 110
The resulting number decreased by its 10% = 110- (10/100*110)
= 110-11 = 99
Now, net decrease =100-99 = 1
Decrease percent = (Decrease / Original number * 100) %
= ( 1 / 100 *100 )% 

Answer 2

Hey

Here is your answer,

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 %.

Hope it helps you!