Question

How to increase a number by a percentage?

Answer 1

Number = n 
percentage = p, in decimal, e.g. 50% = 0.5, 120% = 1.2

10 increased by 50% = n+n*p
= 10 + (10*.5)
=15

n+ (n*p) = number increased by percentage of that number

Answer 2

Any number can be increased if the percentage is more than 100%
for instance
120% of 10
120*10/100 =12
here the number 10 is increased to 12