Python challenge output

Question

below code prints output value of sum as 18... could you please explain it to me ?

b = [0,1,2,3,4,5]

sum = 0
for n in b :
sum += n
if n == 3 :
b.insert(n,10)
if sum > 15:
break
print (sum)
print (b)

Answer 1

10 is inserted at position 3, but then the loop goes on with index 4, where 3 is sitting now, so it will be added again.

1+2+3+3+4+5=18

Answer 2

deleted duplicate entry.... expecting explanation of code output from any1

Answer 3

oh...I got it now.. looking after your result...thanks...

I missed that sum is updated before updating list...