Q:

What is the LCM of 25 and 90?

Accepted Solution

A:
Solution: The LCM of 25 and 90 is 450 Methods How to find the LCM of 25 and 90 using Prime Factorization One way to find the LCM of 25 and 90 is to start by comparing the prime factorization of each number. To find the prime factorization, you can follow the instructions for each number here: What are the Factors of 25? What are the Factors of 90? Here is the prime factorization of 25: 5 2 5^2 5 2 And this is the prime factorization of 90: 2 1 × 3 2 × 5 1 2^1 × 3^2 × 5^1 2 1 × 3 2 × 5 1 When you compare the prime factorization of these two numbers, you want to look for the highest power that each prime factor is raised to. In this case, there are these prime factors to consider: 5, 2, 3 2 1 × 3 2 × 5 2 = 450 2^1 × 3^2 × 5^2 = 450 2 1 × 3 2 × 5 2 = 450 Through this we see that the LCM of 25 and 90 is 450. How to Find the LCM of 25 and 90 by Listing Common Multiples The first step to this method of finding the Least Common Multiple of 25 and 90 is to begin to list a few multiples for each number. If you need a refresher on how to find the multiples of these numbers, you can see the walkthroughs in the links below for each number. Let’s take a look at the multiples for each of these numbers, 25 and 90: What are the Multiples of 25? What are the Multiples of 90? Let’s take a look at the first 10 multiples for each of these numbers, 25 and 90: First 10 Multiples of 25: 25, 50, 75, 100, 125, 150, 175, 200, 225, 250 First 10 Multiples of 90: 90, 180, 270, 360, 450, 540, 630, 720, 810, 900 You can continue to list out the multiples of these numbers as long as needed to find a match. Once you do find a match, or several matches, the smallest of these matches would be the Least Common Multiple. For instance, the first matching multiple(s) of 25 and 90 are 450, 900, 1350. Because 450 is the smallest, it is the least common multiple. The LCM of 25 and 90 is 450. Find the LCM of Other Number Pairs Want more practice? Try some of these other LCM problems: What is the LCM of 139 and 143? What is the LCM of 76 and 144? What is the LCM of 115 and 137? What is the LCM of 32 and 31? What is the LCM of 83 and 85?