Help - Python 26.2 - Let's Do Some Magic

Question

Can anyone explain to me the third line of code? Why has the 'coach' used a "for" loop for a
"while" loop question? I know that they are somewhat interchangeable, albeit "for" loops are more succinct. Where has the "i" come from? How can the program identify what "i" is without prior allocation? What does "range(days)" mean? Is "range" a function or a variable? If it's the latter how come it too has not been given a value? Can someone show me a solution to the question using "while"?

QUESTION
You have a magic box that doubles the count of items you put, in every day.
The given program takes the initial count of the items and the number of days as input.

Task
Write a program to calculate and output items' count on the last day.

Sample Input
3
2

Sample Output
12

Explanation
Day 1: 6 (3*2)
Day 2: 12 (6*2)

CODE
items = int(input())
days = int(input())

for i in range(days):
items *= 2
print(items)

Answer 1

it uses a for loop because it knows exactly how many times it needs to loop. while loops are only for when you don't know

Answer 2

Compiler checks only the output whatever solution we submit.
print(42) is the solution for all challenges if expected output is 42.
All you need to run the while loop until variable days becomes 0.

Answer 3

range is a function that generates the given number of integers stating from zero.
ex:- range(5) means it generates 0, 1, ,2, 3, 4. here 5 doesn't include.(syntax:- range(stop))
range(2, 5) generates 2, 3, 4. here starting number includes but not ending number(syntax(range(start, stop))
range(2, 9, 3) generates 2, 5, 8. here 3 is step i.e. distance between two consecutive numbers less than 9(syntax:- range(start, stop, step))

for i in range(days):
range(days) generates given number of integers and "i" refers to those numbers in the generated order one by one

here is while loop https://code.sololearn.com/cl6L61W8130g

Answer 4

Not sure, I didn't make the app. And just use a counter variable in the while statement

Answer 5

Based on the lesson I went with

while days >= 1:
items = items * 2
days = days - 1

print(items)

Answer 6

But why use a for loop before the lesson on for loops? How could one solve this problem with a while loop?

Answer 7

try this;
items = int(input())
days = int(input())
#your code goes here
i = 1
while i <= days:
items *= 2
i = i + 1

print(items)

Answer 8

without declaring a new variable:

while days > 0:
items = items * 2
days =days- 1
print(items)

you can make it faster, but it works!

Answer 9

While days>0:
Items*=2
days-=1
Print(Items)

Answer 10

n=int(input('Enter the number of items you put every day: '))
p=int(input('Enter the number of days: '))
r=0
q=2*n
for i in range (0,p):
r=q+r
print('Items present on last day: ',r)

Very simple code