The greatest common multiple of any set of integers is infinite.
28
There are five: 105, 126, 147, 168 and 189.
21,42,64,86,108,130,152,174,196,218They are 21, 42, 63, 84, 105, 126, 147, 168, 189, 210.
189 = 3 x 3 x 3 x 7; 105 = 3 x 5 x 7. Common factors are 3 and 7 so LCM = product /HCF ie 189 x 105/21 = 945
21, 42, 63, 84, 105,126, 147, 168, 189, 210 :)
21, 42, 63, 84, 105, 126, 147, 168, 189, 210.
The GCF is 21.
21, 42, 63, 84, 105, 126, 147, 168, 189, 210
21, 42, 63, 84, 105, 126, 147, 168, 189, 210, 231, . . .
42 63 84 105 126 147 168 189 210 and so on ...
21, 42, 63, 84, 105, 126, 147, 168, 189, 210
21, 42, 63, 84, 105, 126, 147, 168, 189, 210