Given a range of first 10 numbers, Iterate from start number to the end number and print the sum of the current number and previous number.

def sumNum(num):
previousNum = 0
for i in range(num):
sum = previousNum + i
print("Current Number", i, "Previous Number ", previousNum," Sum: ", sum)
previousNum = i

print(“Printing current and previous number sum in a given range(10)”)
sumNum(10)

So I do not understand why there is a need for this>>previousNum = i at the end. Please help me understand. Totally beginner to python.
Thank you

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we need to save the previous number somewhere right ? hence we do previousNum = i
Otherwise we will forget.
An alternative way of looking at this is that, we just need to the sum of a number x and
and the number before it ,i.e, x-1 , do we not ? So we can simply loop from 1 to num and
get the sum by doing x + (x-1), i.e, a number and its previous

for i in range(1,10):
# print(f"{i} + {i-1} = { i+(i-1) }")
print(i + (i-1))