Q:

Python Math significance level

I have from a dataset I load in 2 values. 
x1=5.904e-16

and
x1=1.048576e-14

granted these are tiny numbers, but all I want to do is average them. 
avg = 1/2*(x1+x2)

but this gives avg = 0
Arr!

A:

I assume you're using Python 2.
When both arguments are integers, Python 2 uses integer division, which means that the result will also be an integer. For example:
print 1/2
# 0
print 5/2
# 2

To overcome this, either use the float equivalent (0.5), or change one of the arguments to the division (either 1 or 2, doesn't matter) to a float, so that it will return a float as well.
print 1.0/2
# 0.5
print 1/2.0
# 0.5
print 1.0/2.0
# 0.5

You could also, as nneonneo mentioned, put the sum straight into the division, like so:
(x1+x2)/2.0

This will also give the desired result.

