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Arithmetic, relational and Boolean operators

Edexcel IAL Computer Science · WCP02 Practical Programming and Problem-solving

Operators combine values. You need to know exactly what each one returns, especially integer division and modulus.

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Arithmetic operators (spec 7.1.3)

Operator	Meaning	Example	Result
+	add	7 + 2	9
-	subtract	7 - 2	5
*	multiply	7 * 2	14
/	divide (always a float)	7 / 2	3.5
//	integer division (floor)	7 // 2	3
%	modulus (remainder)	7 % 2	1
two asterisks	exponent (power)	7 to the power 2	49

Precedence

Brackets first, then the power operator, then * / // %, then + and -. Operators of equal precedence work left to right. Use brackets to make your intention clear.

print(2 + 3 * 4)
print((2 + 3) * 4)
print(20 - 6 // 4 * 2)
print(-7 // 2, -7 % 2)

Output:

Note: // rounds down (towards minus infinity), so -7 // 2 is -4, not -3.

Relational operators

== (equal to), != (not equal to), <, <=, >, >=. They return True or False. Do not confuse == (comparison) with = (assignment). Strings compare by character codes, so "Zebra" < "apple" is True because capital letters have smaller codes.

Boolean operators

and is True only if both sides are True; or is True if at least one side is True; not reverses a value. Precedence: not, then and, then or.

age = 16
has_ticket = True
print(age >= 18 or has_ticket)
print(age >= 18 and has_ticket)
print(not has_ticket)
print(True or False and False)

Output:

True
False
False
True

Worked example

Use // and % to convert 200 minutes into hours and minutes.

hours = 200 // 60 = 3
minutes = 200 % 60 = 20

Answer: 3 h 20 min

Key idea: / always gives a float; // gives the whole-number quotient rounded down; % gives the remainder; and/or/not combine conditions with not before and before or.

Check yourself

What is displayed when this code runs? ```python print(47 % 5) ```
Show answer
2. 47 = 9 x 5 + 2, so the remainder is 2.
What is displayed when this code runs? ```python print(47 // 5) ```
Show answer
9. 5 goes into 47 nine whole times: 9.
Which of these is displayed when this code runs? ```python print(12 / 4) ```
- 3
- 3.0
- 3.00
- 0
Show answer
3.0. / always returns a float, so the result is 3.0, not 3.
What is displayed when this code runs? ```python print(3 + 4 * 2 ** 2) ```
Show answer
19. The power is first (2 squared = 4), then 4 * 4 = 16, then 3 + 16 = 19.
What is displayed when this code runs? ```python print(-17 // 5) ```
Show answer
-4. -17 / 5 = -3.4, and // rounds down towards minus infinity, giving -4.
What is displayed when this code runs? ```python x = 7 print(x > 5 and x % 2 == 0) ```
- True
- 7
- False
- Error
Show answer
False. x > 5 is True but 7 % 2 == 0 is False; and needs both, so False.
What is displayed when this code runs? ```python a = True b = False c = False print(a or b and c) ```
- True
- False
- None
- a
Show answer
True. and is evaluated first: b and c is False; then a or False is True.
This should print 'valid' only when n is between 1 and 10 inclusive, testing n = 0, 1, 10 and 11. Which line completes it? ```python for n in [0, 1, 10, 11]: __________ print("valid", end=" ") else: print("invalid", end=" ") ```
- `if n >= 1 or n <= 10:`
- `if n >= 1 and n <= 10:`
- `if n > 1 and n < 10:`
- `if not n >= 1:`
Show answer
`if n >= 1 and n <= 10:`. Both limits must hold, so use and with inclusive comparisons: 0 and 11 are invalid, 1 and 10 are valid.

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Last updated 8 November 2026. Spotted a mistake? Tell us.