Run it in your head

Be the computer

Before running code, run it in your head. Write down each variable and update it line by line, like a small table.

It feels slow at first, but it's the fastest way to find out what code *really* does, as opposed to what its names suggest.

Skipping some

total = 0
for i in range(1, 5):
    if i % 2 == 0:
        continue
    total += i * i
print(total)

What does this print?

• 30
• 10
• 20

Counting steps

n = 37
steps = 0
while n != 1:
    n = n // 2 if n % 2 == 0 else n - 1
    steps += 1
print(steps)

What does this print?

• 6
• 5
• 7