126.
7x18 = 126. Then try to factor it down to find another solution.
Another tactic is do multiples of 18 to find the first one divisible by 7.
18 isn't divisible by 7
36 isn't divisible by 7
54 isn't divisible by 7
72 isn't divisible by 7
90 isn't divisible by 7
108 isn't divisible by 7
126 is divisible by 7.
