Operators: Arithmetic, Comparison, and Boolean

This lesson covers the three types of operators you need to know for OCR J277 Section 2.3: arithmetic operators, comparison operators, and Boolean operators (AND, OR, NOT). Operators are the building blocks of expressions and conditions in programming.

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Arithmetic Operators

Arithmetic operators perform mathematical calculations on numerical values.

Operator	OCR Pseudocode	Python	Description	Example	Result
Addition	+	+	Adds two values	7 + 3	10
Subtraction	-	-	Subtracts right from left	7 - 3	4
Multiplication	*	*	Multiplies two values	7 * 3	21
Division	/	/	Divides left by right (real division)	7 / 2	3.5
Integer division	DIV	//	Divides and rounds down to whole number	7 DIV 2	3
Modulus	MOD	%	Returns the remainder after division	7 MOD 2	1
Exponentiation	^	**	Raises to a power	2 ^ 3	8

Understanding DIV and MOD

DIV and MOD are the most commonly tested arithmetic operators in the OCR exam.

DIV gives the whole number part of a division:

• 17 DIV 5 = 3 (because 5 goes into 17 three whole times)
• 10 DIV 3 = 3

MOD gives the remainder:

• 17 MOD 5 = 2 (because 17 = 5 × 3 remainder 2)
• 10 MOD 3 = 1

Common uses of MOD:

• Checking if a number is even: number MOD 2 == 0
• Checking if a number is divisible by another: number MOD n == 0
• Extracting the last digit: 1234 MOD 10 = 4

OCR Exam Tip: DIV and MOD appear in almost every Paper 2 exam. Practise until you can calculate them instantly. Remember: DIV = quotient, MOD = remainder. For example, 23 DIV 7 = 3 and 23 MOD 7 = 2 because 23 = 7 × 3 + 2.

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Comparison Operators

Comparison operators compare two values and return a Boolean result (true or false).