Factor pairs of 20 are any two numbers that, when multiplied together, equal 20. The question to ask is “what two numbers multiplied together equal 20?” Every factor can be paired with another factor, and multiplying the two will result in 20.
To find the factor pairs of 20, follow these steps:
Step 1:
Find the smallest prime number that is larger than 1, and is a factor of 20. For reference, the first prime numbers to check are 2, 3, 5, 7, 11, and 13. In this case, the smallest factor that’s a prime number larger than 1 is 2.
Step 2:
Divide 20 by the smallest prime factor, in this case, 2:
20 ÷ 2 = 10
2 and 10 will make a new factor pair.
Step 3:
Repeat Steps 1 and 2, using 10 as the new focus. Find the smallest prime factor that isn’t 1, and divide 10 by that number. In this case, 2 is the new smallest prime factor:
10 ÷ 2 = 5
Remember that this new factor pair is only for the factors of 10, not 20. So, to finish the factor pair for 20, you’d multiply 2 and 2 before pairing with 5:
2 x 2 = 4
Step 4:
Repeat this process until there are no longer any prime factors larger than one to divide by. At the end, you should have the full list of factor pairs.
Here are all the factor pairs for 20:
(1, 20), (2, 10), (4, 5)
So, to list all the factors of 20: 1, 2, 4, 5, 10, 20
The negative factors of 20 would be: -1, -2, -4, -5, -10, -20