Year 5 Factors & Multiples Detective Pack

Year 5 factors, multiples and prime numbers maths investigation pack with engaging detective games, reasoning challenges and greater-depth activities.
Turn factors and multiples into a full mathematical investigation with this Factor Detective Year 5 Maths Pack.

Designed for the Year 5 UK National Curriculum, this detective-themed resource develops fluency, reasoning and problem-solving skills while exploring factors, multiples, factor pairs, prime numbers, composite numbers and number properties.
Rather than relying on repetitive worksheets, pupils become mathematical detectives: solving mystery numbers, eliminating suspects, testing evidence, identifying false statements and proving their conclusions.
The pack includes:

• 18 Factor Detective Case Files across three challenge levels: Detective, Senior Detective and Chief Inspector
• 6 Open Investigations where pupils must identify a lying witness and solve the mystery number
• Evidence Board with 6 clue trails for use with a 1–100 square – ideal for whole-class or paired reasoning
• Evidence Check with 10 true-or-false statements requiring pupils to justify their answers with mathematical evidence
• Prime Suspects Investigation using systematic elimination on a 1–100 square to discover prime and composite numbers
• 6 Prime Evidence Files providing deeper reasoning and problem-solving challenges
• Pupil recording resources
• Worked answers
• Detailed Teacher Guide explaining how to organise, teach, differentiate and extend each activity

Maths skills covered
The activities give pupils opportunities to:

• identify multiples and factors
• find and use factor pairs
• reason about factors and multiples
• recognise and investigate prime and composite numbers
• identify prime numbers below 100
• use mathematical vocabulary accurately
• eliminate possibilities systematically
• explain mathematical reasoning
• find examples and counterexamples
• spot misconceptions and incorrect reasoning
• justify and prove answers
• tackle greater-depth reasoning and problem solving

Flexible classroom use
The resources can be used for whole-class teaching, independent work, paired investigations, maths centres, interventions, early-finisher challenges, revision or assessment.
The three levels of Factor Detective cards make differentiation straightforward, while the more open-ended investigations and Prime Evidence Files provide opportunities to challenge pupils working at greater depth.
Many of the resources are designed to be low-ink and reusable, making them suitable for printing, laminating and using with multiple classes.
A fun alternative to a traditional factors and multiples worksheet, with plenty of mathematical substance behind the detective theme.

Suitable for Year 5 / Upper KS2.