Class 8 Computer Science — Loops that count

Work out what values a counting loop's variable takes, and how many times its body runs.

Name: ________________________

2.Follow this code by hand. What is product at the end?

product = 1
for n in range(1, 5):
    product = product * n

3.Look hard at the two numbers in the range. How many times does the indented line run?
```
for step in range(5, 5):
    print(step)
```
- a) 1
- b) 10
- c) 0
- d) 5
4.Follow this code by hand. How many numbers does it print altogether?
```
for n in range(2, 7):
    print(n)
    print(n * 10)
```
5.Sort each of these loop headings by how many times the body underneath it would run.
Groups: Three times · Four times
- for n in range(7, 10):
- for n in range(0, 4):
- for n in range(5, 8):
- for n in range(2, 6):
- for n in range(1, 4):
- for n in range(10, 14):
6.The counter starts a long way above zero here. How many times does the indented line run?
```
for n in range(10, 20):
    print(n * 2)
```
7.This loop takes away rather than adds. What is total at the end?
```
total = 100
for n in range(1, 4):
    total = total - n
```
8.A running total climbs inside this loop. What is total at the end?
```
total = 0
for n in range(1, 5):
    total = total + n
```

Answer key — Class 8 Computer Science — Loops that count

1. range(1, 6) → 5; range(4, 9) → 8; range(0, 3) → 2; range(7, 11) → 10; range(2, 15) → 14
2. 24
3. c) 0
4. 10
5. for n in range(1, 4): → Three times; for n in range(0, 4): → Four times; for n in range(5, 8): → Three times; for n in range(2, 6): → Four times; for n in range(7, 10): → Three times; for n in range(10, 14): → Four times
6. 10
7. 94
8. 10