LCM – AMC 8, 2016 – Problem 20
The least common multiple of a and b is 12 .and the lest common multiple of b and c is 15.what is the least possible value of the least common multiple of a and c?
Check the Answer
AMC-8, 2016 problem 20
Challenges and Thrills of Pre College Mathematics
Try with Hints
Find greatest common factors
Can you now finish the problem ……….
Find Least common multiple….
can you finish the problem……..
we wish to find possible values of a,b and c .By finding the greatest common factor 12 and 15, algebrically ,it’s some multiple of b and from looking at the numbers ,we are sure that it is 3.Moving on to a and c ,in order to minimize them,we wish to find the least such that the LCM of a and 3 is 12,$\to 4$.similarly with 3 and c,we obtain 5.the LCM of 4 and 5 is 20 .
Other useful links