Programming
Operators, library routines, and strings
Arithmetic operators, MOD and DIV, ROUND and RANDOM, and string handling with LENGTH, SUBSTRING, UCASE, and LCASE.
Examples use Cambridge pseudocode for the 2026–2028 syllabus.
Arithmetic operators
| Operator | Meaning | Example | Result |
|---|---|---|---|
+ | add | 7 + 2 | 9 |
- | subtract | 7 - 2 | 5 |
* | multiply | 7 * 2 | 14 |
/ | divide | 7 / 2 | 3.5 |
^ | raise to the power | 7 ^ 2 | 49 |
MOD(7, 2) | remainder after division | MOD(7, 2) | 1 |
DIV(7, 2) | whole number division | DIV(7, 2) | 3 |
MOD and DIV
DIV gives how many whole times one number goes into another, and MOD gives what is left over. Together they split a number apart.
A common use: a number is even when MOD(Number, 2) = 0. Another: turning minutes into hours and minutes.
DECLARE TotalMinutes : INTEGER
INPUT TotalMinutes
OUTPUT DIV(TotalMinutes, 60), " hours and ", MOD(TotalMinutes, 60), " minutes"ROUND and RANDOM
ROUND(Value, Places) rounds a real number to a number of decimal places. RANDOM() returns a random number from 0 to 1, which you can scale up.
DECLARE Price : REAL
Price <- 19.987
OUTPUT ROUND(Price, 2)
OUTPUT "Random whole number from 0 to 100: ", ROUND(RANDOM() * 100, 0)Strings are numbered characters
A string is a sequence of characters. In Cambridge pseudocode the first character is at position 1. Click a character to see its position.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|
String handling
| Routine | Returns | Example with "Computer" | Result |
|---|---|---|---|
LENGTH(S) | The number of characters | LENGTH(Word) | 8 |
SUBSTRING(S, Start, Length) | Part of the string | SUBSTRING(Word, 4, 3) | "put" |
UCASE(S) | The string in upper case | UCASE(Word) | "COMPUTER" |
LCASE(S) | The string in lower case | LCASE(Word) | "computer" |
DECLARE FirstName : STRING
DECLARE LastName : STRING
DECLARE Username : STRING
INPUT FirstName
INPUT LastName
Username <- LCASE(SUBSTRING(FirstName, 1, 1)) & LCASE(LastName)
OUTPUT "Your username is ", Username
OUTPUT "It has ", LENGTH(Username), " characters"Exam tip. & joins (concatenates) two strings: "Ada" & "Lovelace" gives "AdaLovelace".
Check yourself
What are MOD(23, 5) and DIV(23, 5)?Show answer
MOD = 3, DIV = 4 (23 = 4 × 5 + 3).
What is SUBSTRING("Keyboard", 4, 5)?Show answer
"board".
Write a condition that is TRUE when N is a multiple of 3.Show answer
MOD(N, 3) = 0.
References used to build these lessons
We used these official documents as references when building this course's lessons. They are the sources for the syllabus structure and course requirements.
Cambridge International · 2210 · Exams 2026–2028