Factor pairs of 140 are any two numbers that, when multiplied together, equal 140. The question to ask is “what two numbers multiplied together equal 140?” Every factor can be paired with another factor, and multiplying the two will result in 140.
To find the factor pairs of 140, follow these steps:
Step 1:
Find the smallest prime number that is larger than 1, and is a factor of 140. 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 140 by the smallest prime factor, in this case, 2:
140 ÷ 2 = 70
2 and 70 will make a new factor pair.
Step 3:
Repeat Steps 1 and 2, using 70 as the new focus. Find the smallest prime factor that isn’t 1, and divide 70 by that number. In this case, 2 is the new smallest prime factor:
70 ÷ 2 = 35
Remember that this new factor pair is only for the factors of 70, not 140. So, to finish the factor pair for 140, you’d multiply 2 and 2 before pairing with 35:
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 140:
(1, 140), (2, 70), (4, 35), (5, 28), (7, 20), (10, 14)
So, to list all the factors of 140: 1, 2, 4, 5, 7, 10, 14, 20, 28, 35, 70, 140
The negative factors of 140 would be: -1, -2, -4, -5, -7, -10, -14, -20, -28, -35, -70, -140