Problem
3. Find the Least Common Multiple (LCM) of 18 and 20. Show how you can use Prime Factors to find this number.
Solution
For this case we can use prime factors descomposition of number like this:
18= 6*3= (2*3)*3= 2* 3^2= 2*3*3
20= 10*2= (5*2)*2= 5*2^2= 5*2*2
From the first case we can see that the numbers with the highest power are:
3^2 , 2^2 and 5, then we can conclude that_
LCM= 2^2 * 3^2 *5 = 4*9*5= 180