Sum a list of numbers in Python

Question

 have a list of numbers such as [1,2,3,4,5...], and I want to calculate (1+2)/2 and for the second, (2+3)/2 and the third, (3+4)/2, and so on. How can I do that?

I would like to sum the first number with the second and divide it by 2, then sum the second with the third and divide by 2, and so on.

Also, how can I sum a list of numbers?

a = [1, 2, 3, 4, 5, ...]

Is it:

b = sum(a)
print b

to get one number?

This is not working for me.

Answer 1

Let us take a list of Numbers and generate the sum of the entire list by using sum

Numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
print (sum(Numbers))

Output

55

Well, for sequence part of the question (1+2)/2, (2+3)/2, ..., (9+10)/2
use a generator and the formula (2*i-1)/2. 
dot is used here to make the values in decimal or floating point.
The first element needs to be skipped when generating the new list

Solution = [(2*i-1)/2. for i in Numbers[1:]]
print(Solution)

Output

[1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5]

print (sum(Solution))

Output

49.5