The GCF is 540.
9 is a factor of 1620.
1620
The largest factor of 1256 is 1256. The largest proper factor of 1256 is 628.
1,2,3,5 (Hint google "factor calculator")
The first 15 multiples of 540: 540, 1080, 1620, 2160, 2700, 3240, 3780, 4320, 4860, 5400, 5940, 6480, 7020, 7560, 8100 . . . ∞
The first 15 multiples of 540: 540, 1080, 1620, 2160, 2700, 3240, 3780, 4320, 4860, 5400, 5940, 6480, 7020, 7560, 8100 . . .
The greatest common factor of 1628 , 40 = 4
21 is the largest factor of 21
36 is the largest factor of 36,
5400
5400
GCD: 18 LCM: 1620