Name: Kathy Heath Who is asking: Parent Level: Elementary
Question: Thanks, Kathy Heath Hi Kathy, You are right that the least common multiple, lcm, of 2, 3 & 9 is 18; I think you have a typo for the lcm {3,4,7} maybe you meant 3, 5 & 7? The lcm{ 3,4, 7} would be 84. lcm{3,5,7} = 105. What you do in general is look at the prime factors of the numbers you're dealing with and then form the lcm by taking the smallest power of each prime that is required. For example: Find the lcm of 54, 150, 28. 54 = 2 * 3^{3}; 30 = 2 * 3*5^{2}; 28 = 2^{2}*7. To find the lcm we need to make a number that has 2^{2}, 3^{3}, 5^{2} and a 7 in it , i.e. lcm{54,150,28] = 4*27*25*7 = 18900. Hope this helps, Denis
