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Grade 8 Computer Science — Blocks and indentation

Read a program's indentation to say which lines belong to which block, and how often each line runs.

Name: ________________________

1.Follow this code by hand. What is count at the end?

count = 0
for n in range(1, 7):
    if n > 2:
        count = count + 1
    count = count + 10

2.Follow this code by hand. How many times does the most deeply indented line run?
```
for n in range(1, 5):
    print(n)
    if n > 100:
        print(n * 2)
```
3.Both of the printing lines are indented here. How many numbers does it print?
```
for n in range(1, 4):
    print(n)
    print(99)
```
4.This program was meant to show the total once, at the very end, but it shows a number four times over. What went wrong?
```
total = 0
for n in range(1, 5):
    total = total + n
    print(total)
```
- a) A program is only allowed to print one number in total
- b) The loop has been written to go round one time too many
- c) The printing line is indented, so it sits inside the loop and runs every trip round
- d) The total is set to 0 on the wrong line of the program

5.This one has an else branch as well. What is total at the end?

total = 0
for n in range(1, 5):
    if n > 2:
        total = total + 1
    else:
        total = total + 100

6.A test sits inside the loop here. What is total at the end?

total = 0
for n in range(1, 6):
    if n > 3:
        total = total + n

7.The last line has been brought back out to the left. What is total at the end?
```
total = 0
for n in range(1, 4):
    total = total + 10
total = total + 1
```
8.Sort each line of this program by how many times it runs.
```
total = 0
for n in range(1, 4):
    total = total + n
    print(n)
print(total)
print(total * 2)
```
Groups: Runs once · Runs three times
- print(total * 2)
- print(n)
- print(total)
- total = 0
- total = total + n

Answer key — Grade 8 Computer Science — Blocks and indentation

1. 64
2.
- 0
- none
3. 6
4. c) The printing line is indented, so it sits inside the loop and runs every trip round
5. 202
6. 9
7. 31
8. total = 0 → Runs once; total = total + n → Runs three times; print(n) → Runs three times; print(total) → Runs once; print(total * 2) → Runs once