Grade 5 · Unit 1: Number and place value

Factors, multiples and primes

HCF, LCM, squares and cubes.

Buses leave a terminal at regular times.

Buses and bells

Bus A leaves every 12 minutes, bus B every 18 minutes. They both leave at 8:00. When will they next leave together? This is a lowest common multiple problem.

LCM

List multiples of each. The first one in both lists is the LCM. 36 minutes: they leave together at 8:36.

HCF

List factors of both. The biggest in both lists is the highest common factor (HCF). HCF of 24 and 36 = 12.

Prime factors and powers

Break a number into prime factors with a factor tree. 60 = 2 × 2 × 3 × 5. Squares: 5² = 25. Cubes: 3³ = 27 is a cube number.

What I learnt

I can find the HCF and LCM.
I can write a number as a product of primes.
I know square and cube numbers.