CODEWITHSUNDEEP
pythonmath
Cassano
Cassano

Reputation: 323

Increase or decrease a number by "x" percentage

How do I increase or decrease an "X" number by a certain amount of percentage say, 2% or 3%?

Case scenario: My value is 5 - I want to increase this number by 2% - so the final value will be 5.1 after 2% percentage increase.

And the same would be if I want to decrease this number by an "X" percentage.

I hope that makes sense, thank you.

Upvotes: 1

Views: 11188

Answers (3)

M. Twarog
M. Twarog

Reputation: 2611

To calculate a percentage in Python, use the division operator (/) to get the quotient from two numbers and then multiply this quotient by 100 using the multiplication operator (*) to get the percentage.

y=int(input("Enter Percentage: "))
x=5
x += (x * y/100)
print(x)

Output:

Enter Percentage: 2
5.1

For Decreasing Value:

y=int(input("Enter Percentage: "))
x=5
x -= (x * y/100)
print(x)

Output:

Enter Percentage: 2
4.9

Upvotes: 3

Rich
Rich

Reputation: 12663

If you want to increase by a percent, multiply the number by (1+{percent}). To decrease by a percent, multiply the number by (1-{percent}). Given your example:

  • Increase 5 by 2%: 5*(1+0.02)=5*1.02=5.1
  • Decrease 5 by 2%: 5*(1-0.02)=5*0.98=4.9.

Upvotes: 1

Samwise
Samwise

Reputation: 71542

A percent is just a fraction of 100, so multiply by 1 + your percent over 100:

>>> x = 5
>>> x *= (1 + 2/100)
>>> x
5.1

Another way to think of it is incrementing x by x times that percent (these operations are algebraically equivalent):

>>> x = 5
>>> x += (x * 2/100)
>>> x
5.1

Upvotes: 1

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