Question

Question 10 Find the LCM of the following numbers: (a) 9 and 4 (b) 12 and 5 (c) 6 and 5 (d) 15 and 4 Observe a common property in the obtained LCMs. Is LCM the product of two numbers in each case?

Class 6 - Math - Playing with Numbers Page 67

Answer 1

LCM of 9&4=36
LCM of 12&5=60
LCM of 6&5=30
LCM of 15&4=60


yes the LCM is the product of two no. in each case

Answer 2

HI !

a) 9 and 4

9 = 3 x 3
4 = 2 x 2
LCM = 2 x 2 x 3  x 2 = 36
product of no:s = 9 x 4 = 36
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b) 12 and 5

12 = 2 x 2 x 3 
5 = 5 x 1 

LCM = 2 x 2 x 3 x 5  = 60
product of no:s = 12 x 5 = 60
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c) 6 and 5

6 = 2 x 3 
5 = 5 x 1

LCM = 2 x 3 x 5 = 30 
product of no:s = 6 x 5 = 30
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d) 15 and 4 

15 = 3 x 5
4 = 2 x 2

LCM = 2 x 2 x 3 x 5 = 60
product of no:s = 15 x 4 = 60


Common property = lcm in all the cases , is a multiple of 3 .
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Yes ,

LCM = product of 2 no:s