Prime Factors and HCF
Question 3 focuses on prime factorisation - breaking numbers down into their basic building blocks. To write 156 as a product of prime factors, you'll need to divide repeatedly by prime numbers (2, 3, 5, 7, 11...).
Start with the smallest primes: 156 ÷ 2 = 78, then 78 ÷ 2 = 39, then 39 ÷ 3 = 13. Since 13 is prime, you're done! So 156 = 2² × 3 × 13.
Finding the highest common factor (HCF) of 156 and 130 means identifying the largest number that divides both. You'll need to find 130's prime factors too, then pick out the common ones.
Pro Tip: Drawing factor trees can help you visualise the process and avoid missing any prime factors!