What is the greatest common factor of 20 and 25?
The greatest common factor of 20 and 25 is 5:The factors of 20 are 1, 2, 4, 5, 10 and 20.The factors of 25 are 1, 5, and 25.The common factors of 20 and 25 are therefore 1 and 5 (and 5 is, of course, the highest).The HCF is: 5