This is my first week having math in person in about a year. The adjustment to having to do it online last march was very difficult as we were all preoccupied with what was going on in the world and the uncertainty of it all. As we move back into in person learning I have seen my grades, mental health and overall happiness go up a significant amount.
This week we learnt how to find the Greatest Commun Factor or GCF. When you are finding a GCF you are essentially finding the largest factor that the numbers share. You do. this process in a few different steps. Here is how:
Step 1: Break the two numbers down in factor trees and find all the prime factors. To make a factor tree you need to keep breaking the number down until you get to a prime number (2,3,5,7,11…)
Step 2: Find all the factors of both numbers and right them all down. If you want to check you did it right, all the factors of its respected number, when multiplied together should equal the number.
Step 3: Looking at the list of number in front of you find the common factors. I circle them for a visual. In this case it would be 3.
Step 4: And just like that you have found the GCF. 3 is the largest number that divides into both 18 and 21. Tip: Even if there are 3 common factors always pick the greatest of them.
Now that we have the basics down, we can use some bigger numbers. Using the same steps, we will be able to find the GCF of any number. In this case I first broke down 78 and 112 into factor trees to find its prime factors. I then wrote out the prime factors and was easily able to identify that 2 is the GCF of 78,112.
Tip: When finding the GCF of bigger numbers instead of using a factor tree you could use a factor ladder which will allow you to stay more organized.
And just like that you now know how to find the Greatest Common Factor of any number big or small.