A number is divisible by 6 when it is divisible by 2 and 3 both.
The three digit number can be ¯a¯b¯2.
a+b can be 4,7,10
If a+b=4 then (a,b) can be (1,3), (3,1), (2,2)
If a+b=7 then (a,b) can be(2,5),(5,2),(3,4),(4,3)
If a+b=10 then (a,b) can be (5,5)
So, 8 such cases when 2 is at unit's place
Similarly, there exist 8 such cases when 4 is at unit's place.
Total =16 cases.
Hence this is the required answer.