Lowest common multiple and prime factors

Lowest common multiple and prime factors

Lesson details

Key learning points

  1. In this lesson, we will use prime factorisation to identify common multiples and the lowest common multiple. We will also use Venn diagrams to sort prime factors.

Licence

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5 Questions

Q1.
Find the lowest common multiple of 3 and 6
18
2
3
Correct answer: 6
Q2.
Find the highest common factors of 3 and 6
18
2
Correct answer: 3
6
Q3.
Find the LCM of 14 and 21
2 and 3
21
294
Correct answer: 42
7
Q4.
A pair of numbers have LCM OF 24. What could the pair of numbers be?
12 and 2
24 and 48
6 and 4
Correct answer: 8 and 3
Q5.
Zaki says that 2 prime numbers LCM is found by multiplying the prime numbers together, Is this true or false?
False
Correct answer: True

5 Questions

Q1.
Fill in the gaps, in the correct order: Writing numbers as a __________ of their _______ factors helps you to find the lowest common multiple.
product, common
Correct answer: product, prime
subtraction, common
subtraction, prime
Q2.
The Venn diagram shows the prime factors of 60 and 84. Write 60 as a product of its prime factors.
Correct answer: 2 × 2 × 3 × 5
2 × 2 × 3 × 7
2 × 2 × 3 × 7 × 5
2, 2, 3, 5
Q3.
The Venn diagram shows the prime factors of 60 and 84. Write 84 as a product of its prime factors.
2 × 2 × 3 × 5
Correct answer: 2 × 2 × 3 × 7
2 × 2 × 3 × 7 × 5
2, 2, 3, 5
Q4.
The Venn diagram shows the prime factors of 60 and 84. Which calculation represents the LCM of 60 and 84?
2 × 2 × 3 × 5
Correct answer: 2 × 2 × 3 × 5 × 7
2 × 2 × 3 × 7
2 × 2 × 3 × 7 × 2 × 2 × 3 × 5
Q5.
The Venn diagram shows the prime factors of 60 and 84. What is the LCM of 60 and 84?
12
Correct answer: 420
5040
60

Lesson appears in

UnitMaths / Prime factor decomposition