How do you round UP a number?

Question

How does one round a number UP in Python?

I tried round(number) but it rounds the number down. Example:

round(2.3) = 2.0 

and not 3, as I would like.

The I tried int(number + .5) but it round the number down again! Example:

int(2.3 + .5) = 2

Answer 1

The math.ceil (ceiling) function returns the smallest integer higher or equal to x.

For Python 3:

import math
print(math.ceil(4.2))

For Python 2:

import math
print(int(math.ceil(4.2)))

Answer 2

I know this answer is for a question from a while back, but if you don't want to import math and you just want to round up, this works for me.

>>> int(21 / 5)
4
>>> int(21 / 5) + (21 % 5 > 0)
5

The first part becomes 4 and the second part evaluates to "True" if there is a remainder, which in addition True = 1; False = 0. So if there is no remainder, then it stays the same integer, but if there is a remainder it adds 1.

Answer 3

Interesting Python 2.x issue to keep in mind:

>>> import math
>>> math.ceil(4500/1000)
4.0
>>> math.ceil(4500/1000.0)
5.0

The problem is that dividing two ints in python produces another int and that's truncated before the ceiling call. You have to make one value a float (or cast) to get a correct result.

In javascript, the exact same code produces a different result:

console.log(Math.ceil(4500/1000));
5