Grade 9 Computer Science — Building a list as you go

1.Look hard at the range before working anything else out. How many values does this list end up with?

empty = []
for n in range(5, 5):
    empty.append(n)
print(len(empty))

2.A running total is appended each time round here, so the list holds the totals rather than the values. What does the program print?

totals = []
running = 0
for n in range(1, 5):
    running = running + n
    totals.append(running)
print(totals[3])

3.The test in this one is about the counter doubled rather than the counter itself. How many values does the list end up with?

evens = []
for n in range(0, 12):
    if n * 2 < 10:
        evens.append(n)
print(len(evens))

4.This program starts with an empty list and puts one value into it each time round. How many values does it end up with?

squares = []
for n in range(1, 5):
    squares.append(n * n)
print(len(squares))

5.One loop sits inside another here, and the appending is in the deeper of the two. What does the program print?

pairs = []
for a in range(0, 3):
    for b in range(0, 4):
        pairs.append(a + b)
print(len(pairs))

• a) 4
• b) 3
• c) 7
• d) 12

6.Work out what this program prints. The values are not the counter itself this time.

doubles = []
for n in range(3, 7):
    doubles.append(n * 2)
print(doubles[2])

7.There are two appends inside this loop rather than one. How many values does the list end up with?

names = []
for n in range(1, 4):
    names.append(n)
    names.append(n * 10)
print(len(names))

8.Only some of the counter's values get into this list. What does the program print?

found = []
for n in range(1, 8):
    if n * n > 20:
        found.append(n)
print(found[0])

• a) 25
• b) 4
• c) 6
• d) 5