Answer:

The answer to your query is 4

1. Decompose all numbers into prime factors

644 2

322 2

161 7

23 23

1

1044 2

522 2

261 3

87 3

29 29

1

2. Write all numbers as the product of its prime factors

Prime factors of 644 = 2^2 . 7 . 23

Prime factors of 1044 = 2^2 . 3^2 . 29

3. Choose the common prime factors with the lowest exponent

Common prime factors: 2

Common prime factors with the lowest exponent: 22

4. Calculate the Greatest Common Factor or GCF

Remember, to find the GCF of several numbers you must multiply the common prime factors with the lowest exponent.

GCF = 2^2 = 4