Answer:
5
Step-by-step explanation:
This trick works with 3:
If the sum of the digits of a number is divisble by 3 then the number is divisble by 3.
44 is not divisble by 3 because 4+4=8 is not divisble by 3.
45 is divisble by 3 because 4+5=9 is divisble by 3.
46 is not divisble by 3 because 4+6=10 is not divisble by 3.
47 is not divisble by 3 because 4+7=11 is not divisble by 3.
54 is divisble by 3 because 5+4=9 is divisble by 3.
55 is not divisble by 3 because 5+5=10 is not divisble by 3.
56 is not divisble by 3 because 5+6=11 is not divisble by 3.
57 is divisble by 3 because 5+7=12 is divisble by 3.
64, 65,67 are not divisble by 3 because their digits' sums are 10,11, and 13 respectively. 66 is a winner because 6+6=12 is divisble by 3.
Finally 7...
74,76,77 are not divisble by 3 because their digits' sums are 11,13, and 14 respectively. 75 is divisble by 3 because 7+5=12 is divisble by 3.
The victors are
45
54
57
66
75
