HCF & LCM – Prime Factorisation – Messenger! In this competitive activity, one student at a time acts as a messenger for their team of 2 or more students. Without running (!), they relay information about questions (posted around the room) to their teammates who then answer them. Students need to record the question letter and the answer so they can mark their work using the answer slide at the end of the activity. With the points system, students can attempt appropriate questions. You could choose posters/questions to include and delete others. (Clear plastic wallets around your classroom make it quick and easy to display posters.)

Printing To print handouts from slides - Select the slide from the left. Then click: File > Print > ‘Print Current Slide’ To print multiple slides - Click on a section title to highlight all those slides, or press ‘Ctrl’ at the same time as selecting slides to highlight more than one. Then click: File > Print > ‘Print Selection’

Messenger! Title Slide

10 In teams pick a messenger! It’s their job to collect questions for the rest of the team to answer. You can change who is the messenger but only one person is allowed to stand up at once and they can’t carry a pen or paper to the question! Each question is worth a different number of points! Record the question letter and your answer on a single piece of paper. After marking, the team that scores the most points wins! 10 Optional rules slide to show the class.

45 120 4 3 Question B Question A Find the prime factors of:

72 900 4 3 Question D Question C Find the prime factors of:

22 × 3 × 5 22 × 3 × 52 3 3 Question F Question E What number is this the prime factorisation for? What number is this the prime factorisation for? 22 × 3 × 5 22 × 3 × 52

Question G Question H 4 4 What are the two numbers shown in this Venn diagram? What are the two numbers shown in this Venn diagram? 2 2 2 3 3 5 3 2 2 3 5

Question I Question J 5 6 What are the two numbers shown in this Venn diagram? What are the two numbers shown in this Venn diagram? 5 2 2 5 2 3 3 3 2 5 2 What is the Highest Common Factor and Lowest Common Multiple of the numbers? What is the Highest Common Factor and Lowest Common Multiple of the numbers?

40 & 90 60 & 150 6 6 Question L Question K Find the Highest Common Factor of Find the Highest Common Factor of 40 & 90 60 & 150

24 & 40 250 & 75 7 7 Question N Question M Find the Lowest Common Multiple of Find the Lowest Common Multiple of 24 & 40 250 & 75

150 & 90 12 & 45 8 8 Question P Question O Find the HCF and LCM of

8 7 Question Q Question R 3 2 2 3 5 The HCF of A and B is 12. Complete the overlapping part of the Venn diagram. The HCF of A and B is 50. Complete the overlapping part of the Venn diagram. A B A B 3 2 2 3 5 What numbers are A and B? What numbers are A and B?

9 9 Question T Question S 2 5 2 3 2 3 The LCM of A and B is 540. Complete the overlapping part of the Venn diagram. The LCM of A and B is 720. Complete the overlapping part of the Venn diagram. A B A B 2 5 2 3 2 3 What numbers are A and B? What numbers are A and B?

9 9 Question V Question U Two numbers have a HCF of 10 and an LCM of 150. Neither of the numbers is 10 or 150. What are the numbers? Two numbers – both lower than 30 – have a HCF of 6 and an LCM of 72. What are the numbers?

10 10 Question X Question W Two numbers have a HCF of 30 and an LCM of 180. Both numbers are greater than 50. What are the numbers? Two numbers have a HCF of 35 and an LCM of 1050. Both numbers are smaller than 300. What are the numbers?

12 11 Question Z Question Y Copy the diagram and use it to find the HCF and LCM of 27, 126 & 180. Write the LCM in prime factorisation form with indices. Copy the diagram and use it to find the HCF and LCM of 30, 60 & 225.

N O P Q R S T U V W X Y Z A B C D E F G H I J K L M 3 7 4 8 9 5 10 6 Qu. Answer Points A 32 x 5 3 B 23 x 3 x 5 4 C 2 x 62 D 22 x 32 x 52 E 60 F 300 G 20 & 45 H 120 & 90 I 40 & 24: HCF = 8, LCM = 120 5 J 90 & 300: HCF = 30, LCM = 900 6 K HCF = 10 L HCF = 30 M LCM = 120 7 Qu. Answer Points N LCM = 750 7 O HCF = 30, LCM = 450 8 P HCF = 3, LCM = 180 Q 36 & 24 R 500 & 150 S A = 108, B = 90 9 T A = 180, B = 240 U 30 & 50 V 24 & 18 W 90 & 60 10 X 210 & 175 Y HCF = 15, LCM = 900 11 Z HCF = 9, LCM = 22 x 33 x 5 x 7 12 Answers to display so students can mark their own or another team’s work.

Answers to display so students can mark their own or another team’s work.

tom@goteachmaths.co.uk Questions? Comments? Suggestions? …or have you found a mistake!? Any feedback would be appreciated . Please feel free to email: tom@goteachmaths.co.uk