1, 2, 4, 5, 10, 20
1, 2, 3, 5, 6, 10, 15, 30
LCM for 20 and 30 is 60.
21,22,23,24,25,26,27,28,29
All of them except 23 and 29 which are prime numbers having only two factors
Common factors of 28 and 30 are: 1 and 2.
Including 20 and 30 there are ten of them
1, 2, 3 and 6
A common denominator of 20 and 30 is 600. This is NOT the least common denominator, though.
The prime numbers between 20 and 30 are 23 and 29.
The factors of 30 are: 1, 2, 3, 5, 6, 10, 15, 30 The factors of 36 are: 1, 2, 3, 4, 6, 9, 12, 18, 36
120
The LCM is: 90
GCF = 3