Topic 0 · Programming Fundamentals (Python)

Chapter 1 · Sequence, selection & iteration

📋 Reference · always available

Variable

A named box in memory. `x = 25` stores 25; a later `x = 78` replaces it.

= vs ==

`=` stores a value; `==` tests equality.

// and %

`//` floor-divides; `% 10` gives the last digit, `// 10` drops it.

while loop

Repeat *while* a condition is true: init → test → update, or it never stops.

for / range

`for i in range(a, b):` runs i = a … b−1 → b−a times.

if / elif / else

Runs the FIRST true branch only; put narrow conditions first.

Tracing

Track every variable line-by-line — the #1 exam skill.

IB pseudocode

`loop while … end loop`, `if … then … end if`, `output` — exam answers use this, not Python.