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What does this program print?

for number in range(2, 10, 3):
    print(number)

2, 5 and 8, each number on a line of its own
2, 5, 8 and 11
3, 6 and 9
2, 3, 4, 5, 6, 7, 8 and 9

2, 5 and 8, each number on a line of its own
The sequence starts at 2 and goes on in steps of three until the next number, 11, would reach the limit of 10.

range(start, end, step) begins at start, counts in steps of step and stops before end: 2, 5, 8.

How often does for i in range(5): print(""Hello"") print the greeting?

Four times
Five times
Six times

Five times
The numbers 0 to 4 make five rounds.

With one argument, range() starts at 0 and ends before the number, and so range(5) gives exactly five numbers and the loop five rounds.

What does this program print?

total = 0
for number in [4, 7, 1, 8]:
    if number > 3:
        total += number
print(total)

20
19
3
8

19
4 + 7 + 8 = 19, because only these three numbers are greater than 3.

The accumulator starts at 0, and in every round in which the number is greater than 3 it is added: 4, then 11, then 19.

Someone wants to add up the prices and gets 3.5. Why?

for price in [2.5, 1.0, 3.5]:
    total = 0
    total += price
print(total)

print() is in the wrong place and should be indented.
total = 0 is in the body and resets the sum in every round.
+= does not calculate reliably with decimal numbers.

total = 0 is in the body and resets the sum in every round.
Right: the line belongs before the loop, and then the result is 7.0.

An accumulator gets its starting value before the loop. In the body it is set back to 0 in every round, and at the end it holds only the last price.

What does this program print?

number = 100
rounds = 0
while number > 10:
    number = number // 2
    rounds += 1
print(rounds, number)

4 6
3 12
4 6.25
5 3

4 6
100 becomes 50, 25, 12 and 6, and at 6 the condition number > 10 no longer holds.

The condition is checked before every round: 100, 50, 25 and 12 are greater than 10, 6 no longer is. That gives four rounds and the final value 6.

Which of these loops never stop if count is 0 beforehand? (several are right)

while count < 3: print(count)
while count < 3: count += 1
while count < 3: count -= 1
while count > 3: count += 1

while count < 3: print(count)
The body only prints and never changes count.
while count < 3: count -= 1
count keeps getting smaller and therefore stays below 3 for ever.

A while loop ends only if its body eventually makes the condition false. If a program in the browser does not stop, the Stop button ends it.

For which tasks is while the right loop? (several are right)

Writing every item of a shopping list on a line of its own
Asking for the age until a number above 0 is entered
Printing the numbers from 1 to 10
Working out after how many years savings have doubled

Asking for the age until a number above 0 is entered
How many attempts it takes only shows up while asking.
Working out after how many years savings have doubled
The number of years is exactly what the loop is meant to find out.

for fits when a list, a text or a fixed number of rounds sets the course, while when the end only shows up in the loop.

What does this program print?

for number, item in enumerate([""milk"", ""bread""], start=1):
    print(number, item)

0 milk and 1 bread
1 milk and 2 bread
milk 1 and bread 2

1 milk and 2 bread
With start=1 the number begins at 1.

enumerate() gives the number and the element in every round, the loop shares them out to number and item, and start=1 makes counting begin at 1.