Counters and totals in a Python loop

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which line should go BEFORE the loop to start a counter?

A count = 0

B count += 1

2. Which line adds 1 to count each time the loop repeats?

A count = 1

B count += 1

3. Where should total = 0 be placed to build a running total?

A Before the loop starts

B Inside the loop, at the top

4. Which line adds the number stored in score to a running total?

A total += score

B total = score

5. What is count after this code runs? count = 0 for i in range(4): count += 1

A 1

B 4

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1count += 1		Acount = 0 for i in range(5): count += 1
2total += score		B=+ is written instead of +=, so total is just set to n each time instead of adding to it. It should be total += n.
3Set a counter to 0 before the loop so it starts with nothing counted		CAdds the value of score onto total, building a running total inside the loop
4Add each number from a list to a running total inside a for loop		Dtotal = 0 for n in marks: total += n
5for i in range(5): count = 0 count += 1		Ecount is set to 0 inside the loop, so it resets every repeat and always ends up as 1. It should be set to 0 before the loop.
6total = 0 for n in marks: total =+ n		FAdds 1 to the variable count each time it runs, so it counts how many times the loop repeats

Definitions

count += 1

Fill in the Blanks

Complete each line of code by filling in the missing parts.

count = _ for i in range(5): count += 1

total = 0 for n in range(1, 4): total __ n

score = 0 for n in [4, 7, 9]: score += _

count = 0 for name in ["Mia", "Leo"]: count += _

_____ = 0 for p in [5, 10, 15]: total += p

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A count = 0

B for i in range(5):

C count += 1

D print(Count)

Question 2

A total = 1

B for n in range(1, 4):

C total += n

D print(total)

Question 3

A count = 0

B while count < 3

C count += 1

D print(count)

Question 4

A total = 0

B for n in [4, 6, 10]:

C total += 1

D print(total)

Question 5

A score = 0

B for i in range(3):

C score += 10

D print('Score:' score)

Answer Key

Counters and totals in a Python loop

Section A: Quick Questions

A — count = 0

B — count += 1

A — Before the loop starts

A — total += score

B — 4

Section B: Match the Pairs

count += 1 → Adds 1 to the variable count each time it runs, so it counts how many times the loop repeats

total += score → Adds the value of score onto total, building a running total inside the loop

Set a counter to 0 before the loop so it starts with nothing counted → count = 0 for i in range(5): count += 1

Add each number from a list to a running total inside a for loop → total = 0 for n in marks: total += n

for i in range(5): count = 0 count += 1 → count is set to 0 inside the loop, so it resets every repeat and always ends up as 1. It should be set to 0 before the loop.

total = 0 for n in marks: total =+ n → =+ is written instead of +=, so total is just set to n each time instead of adding to it. It should be total += n.

Section C: Definitions

count += 1 — Set count = 0 before a loop, then use count += 1 inside it to add 1 each repeat. Use total += value to build a running total.

Section D: Fill in the Blanks

count = 0
for i in range(5):
    count += 1

total = 0
for n in range(1, 4):
    total += n

score = 0
for n in [4, 7, 9]:
    score += n

count = 0
for name in ["Mia", "Leo"]:
    count += 1

total = 0
for p in [5, 10, 15]:
    total += p

Section E: Spot the Error

D — Python cares about capital letters. The variable is called count, not Count, so Count causes a NameError. It should be print(count).

A — A running total must start at 0 before the loop. Starting at 1 makes the answer 1 too big. It should be total = 0.

B — A while line must end with a colon. It should be while count < 3:

C — This adds 1 each time, so it counts the repeats instead of adding up the numbers. To build a running total, use total += n.

D — The items inside print() need a comma between them. It should be print('Score:', score).