Make sure that 20 is a factor of both numbers and that they do not have any other common factors.
Example Solution: 20 and 40
Practice makes perfect
Factors that are shared by two or more numbers are called common factors. The greatest of the common factors is called the greatest common factor (GCF). We want to write a pair of numbers with the given GCF.
20
We need to keep two things in mind to find this pair of numbers.
20 must be a factor of both numbers.
The numbers cannot have any common factors that are greater than 20.
The easiest way to do this is to multiply 20 by 1 to get the first number and then multiply 20 by 2 to get the second number. This way lets us be sure that 20 is a factor of both numbers and that the pair does not have any greater common factors.
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First Number & Second Number
20* 1= 20 & 20* 2= 40
Two numbers whose greatest common factor is 20 are 20 and 40. This is just one of many possible solutions.
Checking Our Answer
We can check our answer by finding the greatest common factor of 20 and 40 and verifying whether it is 20. We do this by listing all of the factors of 20 and 40, then identifying the greatest of the common factors.
Factors of20:& 1, 2,4,5,10, 20
Factors of40:& 1,2,4,5,8,10, 20,40
We can see that the GCF of 20 and 40 is 20. Our answer is correct!
