The number is two.
60
6*9=54 so they both go into it evenly, but the lowest number is 18.
60
60
1, 2, 3, 6, 9, 18, 27, 54.
3,5,
2.
Their lowest common multiple is 378
54 doesn't go evenly into 77. 54 goes into 77 once with a remainder of 23.
6 is the largest number that will go into both
60