Factor pairs of 128 are any two numbers that, when multiplied together, equal 128. The question to ask is “what two numbers multiplied together equal 128?” Every factor can be paired with another factor, and multiplying the two will result in 128.
To find the factor pairs of 128, follow these steps:
Step 1:
Find the smallest prime number that is larger than 1, and is a factor of 128. 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 128 by the smallest prime factor, in this case, 2:
128 ÷ 2 = 64
2 and 64 will make a new factor pair.
Step 3:
Repeat Steps 1 and 2, using 64 as the new focus. Find the smallest prime factor that isn’t 1, and divide 64 by that number. In this case, 2 is the new smallest prime factor:
64 ÷ 2 = 32
Remember that this new factor pair is only for the factors of 64, not 128. So, to finish the factor pair for 128, you’d multiply 2 and 2 before pairing with 32:
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 128:
(1, 128), (2, 64), (4, 32), (8, 16)
So, to list all the factors of 128: 1, 2, 4, 8, 16, 32, 64, 128
The negative factors of 128 would be: -1, -2, -4, -8, -16, -32, -64, -128