What are the common factor of 36 and 54?

Answer 1

The common factors of 54 and 36 are: 1, 2, 3, 6, 9, and 18

The difference between the two numbers is 18. 18 is also half of the smaller of the two numbers. The smaller of these calculations will be the upper limit of all possible common factors. Start with 18 and go down until you find a number that divides into both. 36 / 18 = 2 and 54 / 18 = 3. Yep, that works, so 18 is a common factor. Now you just need to find all of the numbers that will divide evenly into 18.
The common factors are: 1, 2, 3, 6, 9 and 18.

54-1,2,3,6,9,18,27,54

36-1,2,3,4,6,9,12,18,36

Answer 2

Prime factor both and choose all the factors that are common to multiply.

36=2x2x3x3

54=2x3x3x3

2x3x3=18