Tuesday June 6th – LCM’s and HCF’s

LEARNING OBJECTIVE: To understand and solve LCM and HCF problems

SUCCESS CRITERIA: You will be able to solve LCM and HCF problems:

Level C	Find The LCM of two simple numbers Find the HCF of two simple numbers Write a number as a product of its prime factors
Level B	Find the LCM of two or more numbers Find the HCF of two or more numbers

STARTER:

1. Find the common factors of 42 and 70 and write down the Highest Common Factor
   
2. Find the LCM of the following sets of numbers
   
   1. 36, 45 and 54
      
   2. 14, 56 and 84
      
   3. 60, 75 and 90
      

LESSON: Remind students of what is meant by Lowest common Multiple and Highest Common Factor using questions above.

LCM Lesson, HCF Lesson if needed. Indian Method

Questions

1. The HCF of two numbers if 7. Give a possible pair of numbers
   
2. The HCF of three number is 15. Give a possible set of three numbers.
   
3. Find the LCM of the following sets of numbers
   
   1. 6 and 8
      
   2. 5 and 9
      
   3. 12 and 20
      
   4. 2, 3 and 5
      
   5. 6, 18 and 24
      
   6. 3,4 and 7
      
4. Tracy says that the LCM of 24 and 60 is 12. Is she correct? Explain your answer
   

More questions on Worksheet

PLENARY: Checking answers together, discussion on answers