Exam Tips & Common Mistakes

Key Tips:

• Factor pairs: Always work systematically to avoid missing factors
• Prime factors: 1 is NOT a prime number (has only 1 factor, not 2)
• HCF: Cannot be larger than the smaller number
• LCM: Cannot be smaller than the larger number
• Check: HCF × LCM = product of the two numbers

Common Mistakes:

• ❌ Forgetting that 1 and the number itself are always factors
• ❌ Thinking 1 is prime (it's neither prime nor composite)
• ❌ Confusing HCF and LCM (HCF divides both, LCM is divisible by both)
• ❌ Not using systematic methods for large numbers
• ❌ Making arithmetic errors in factor trees

Memory Aids:

• FACTORS: "Divide IN" - factors divide into the number
• MULTIPLES: "Times table" - multiply the number
• HCF: "Highest that goes into both"
• LCM: "Lowest that both go into"